Develop Bugs

Slow 4G Speeds, connectivity issues. Modem, Baseband

Basically the Redmi note 5 Pro and Ai are really slow for internet speeds, unstable I compared it to Samsung S7. This post talks about the same problem.
https://forum.xda-developers.com/redmi-note-5-pro/how-to/low-signal-poor-4g-speeds-t3777925
It was so slow i was going to sell this.
When using a custom roms, the LTE connection would turn off even tho it was turned on, you click it and it says turn off LTE connection even tho it's already stopped working, no LTE icon present. Then after turning it off and turning it back on it works again, till it randomly disconnects itself again. Restarting the phone while LTE was working would normally mean it had the same problem when phone started up, LTE icon missing internet not working you click on it and it says turn it off, it's on but not working.
MIUI didn't seem to disconnect those issues above still hopelessly slow speeds however.
I found someone else who suggested flashing a modem to fix it, however this didn't work for me as there's a massive list modems i tried and didn't fix it below. Had to use aeroplane mode after each modem flash and turn it off and wait a bit before turning on LTE to get a connection.
What did fix it was this post i came across from another person.
As far as I see it's issue with MIUI9. What is my conclusion so far is, with MIUI9, there is an issue with network switching like from 4g to 2g or 3g and the phone gets briefly disconnected from network . This is more often when you use data than voice.
I use two sim cards so I've currently got my data sim set to LTE only and my calling sim is just on WCDMA as soon as i did that my download speeds match my S7 just as fast which wasn't even close to been possible before i did this. So i'm convinced that the persons post is correct and it keeps disconnecting from 4G to try and connect to 3G and results in an unstable connection. That and i ran speedtests against all those modems listed and couldn't get these speeds.
It might be possible to set my calling sim to WCDMA/LTE and data to only LTE not tested so far, so its working but if i lose LTE connection it would normally drop to WCDMA so with LTE only that could be problematic. Doesn't seem to disconnect anymore and maintains the LTE during phone restarting.

This is a list of all the modem, baseband files i tried.
These where from China rom.
9.5.16.0
8.8.9
8.8.3
8.6.28
8.6.21
8.6.16
The rest were Global, Stable and Beta
10.0.1.0
9.6.4.0
9.6.3.0
9.5.17
9.5.14.0
9.5.13.0
9.5.6.0
9.2.7.0
8.9.20
8.9.13
8.9.6
8.8.30
8.8.23
8.8.16
8.8.2
8.7.26
8.7.12
8.7.5

I just got the Mi 8 Lite yesterday. The speeds showing for mobile data on the phone are really slow... and downloads from the Play Store take forever (a few seconds for each MB). Trying to download the Android 9.0 update was painfully slow. Eventually I resorted to putting the SIM back into my old device and using that as a hotspot to update my phone via "wi-fi".
I have now placed the SIM back into the Mi 8 Lite and the mobile speeds are still slow. I'm really confused, however, because when I use the Mi 8 Lite as a hotspot to share the data with my old device, the downloads on that phone are quick.
So it seems that the Mi 8 Lite is just struggling to make internal use of the data speed that it is actually receiving from my network... it still transfers the full speed to other devices via the hotspot.
Any suggestions?

Please post radio issues (and fixes) here

**EDIT**
Forgot the random outgoing call issue.
Since getting my OP8P, it doesn't seem like any of the radio issues have really been satisfactorily addressed. I'm not sure if there is anything that can be done on our end to fix them, but I figured I'd create a thread to track them, and fix them if possible.
Please include your carrier, or any other differentiating factors:
MMS issues (T-Mobile): MMS messages do not come in reliably or at all with wifi enabled. SMS and RCS messages are not affected.
Fix: (Workaround) Disable VoWifi, which doesn't seem to work on as many APs as the OP7P and prior did. If that doesn't work, turn off wifi altogether to allow messages to send/receive.
--------------------------------------------------------
Wifi calling issues (T-Mobile): Wifi calling will not stay activated. Icon appears for about 30 seconds after turning on wifi. Also seems to be affecting MMS messages not sending/receiving when connected to WiFi, and potentially outgoing calls not going through reliably.
Fix: (Workaround) Possibly affected by APs that allow TKIP encryption method. Reports of only allowing AES/CMAK helping. TKIP has known vulnerabilities, but older devices may still require it be enabled.
--------------------------------------------------------
Wifi connection issues: Wifi seems to go dead 1-3 times a day. Wireless still shows a strong connection, but no data actually passes (SMS still works).
Fix: (Workaround) toggle wifi
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Poor 5G performance (T-Mobile): While this could be a T-Mobile issue, as they seem to have turned on 5G over most of our area using UHF bands (300mhz to 3ghz), performance is pretty choppy. Uploads seem to be more negatively affected, with speeds less than 1mbps at times. Download speeds can be up to LTE speeds, but often are not, and are almost always jumpy and not smooth during speed tests.
Potential fix: Disable 5G under: SIM & network settings > Preferred network type
--------------------------------------------------------
Occasion outbound call issue: Sometimes making an outgoing call takes 2 or 3 tries. I can't remember the error, off the top of my head, but it's something like "service not available".
--------------------------------------------------------
Can ONLY receive MMS on WiFi calling not on mobile data, SMS not affected. (details here)
Fix: use 3rd party SMS app, revoke all permissions from stock app, disable stock app

Flapjack said:
Since getting my OP8P, it doesn't seem like any of the radio issues have really been satisfactorily addressed. I'm not sure if there is anything that can be done on our end to fix them, but I figured I'd create a thread to track them, and fix them if possible.
Please include your carrier, or any other differentiating factors:
MMS issues (T-Mobile): MMS messages do not come in reliably or at all with wifi enabled. SMS and RCS messages are not affected.
Fix: (Workaround) Turn off wifi. Not really feasible, though... especially those not on unlimited data plans.
--------------------------------------------------------
Wifi calling issues (T-Mobile): Wifi calling will not stay activated. Icon appears for about 30 seconds after turning on wifi.
Fix: (Workaround) Possibly affected by APs that allow TKIP encryption method. Reports of only allowing AES/CMAK helping. TKIP has known vulnerabilities, but older devices may still require it be enabled.
--------------------------------------------------------
Wifi connection issues: Wifi seems to go dead 1-3 times a day. Wireless still shows a strong connection, but no data actually passes (SMS still works).
Fix: (Workaround) toggle wifi
--------------------------------------------------------
Poor 5G performance (T-Mobile): While this could be a T-Mobile issue, as they seem to have turned on 5G over most of our area using UHF bands (300mhz to 3ghz), performance is pretty choppy. Uploads seem to be more negatively affected, with speeds less than 1mbps at times. Download speeds can be up to LTE speeds, but often are not, and are almost always jumpy and not smooth during speed tests.
Fix: None, unless there's a way to disable 5G for now (if that would even help).
Click to expand...
Click to collapse
You can disable 5G in the SIM and Network settings ??*

With my old phone if I disable wifi it connects to Lte instantly and I can start surfing. With my 1+ now if I disable wifi it takes about 10sec until there's Lte but I can't start surfing. I have to switch from Lte to 2g and back to get it working. Same Sim in both phones

XD-MOD2-9MM said:
You can disable 5G in the SIM and Network settings ??*
Click to expand...
Click to collapse
Good grief. I have no idea how I missed that. Thanks! I'll test and update the thread if LTE performance seems better than 5G. This very well could be a T-Mobile thing, since they just recently turned it on in my area.
Flatric said:
With my old phone if I disable wifi it connects to Lte instantly and I can start surfing. With my 1+ now if I disable wifi it takes about 10sec until there's Lte but I can't start surfing. I have to switch from Lte to 2g and back to get it working. Same Sim in both phones
Click to expand...
Click to collapse
I have noticed the exact same thing. I'm not sure why it takes so long... especially with dual-channel network acceleration enabled (and the fact that VoLTE is established before I shut wifi off).

Flapjack said:
**EDIT**
Forgot the random outgoing call issue.
Since getting my OP8P, it doesn't seem like any of the radio issues have really been satisfactorily addressed. I'm not sure if there is anything that can be done on our end to fix them, but I figured I'd create a thread to track them, and fix them if possible.
Please include your carrier, or any other differentiating factors:
MMS issues (T-Mobile): MMS messages do not come in reliably or at all with wifi enabled. SMS and RCS messages are not affected.
Fix: (Workaround) Turn off wifi. Not really feasible, though... especially those not on unlimited data plans.
--------------------------------------------------------
Wifi calling issues (T-Mobile): Wifi calling will not stay activated. Icon appears for about 30 seconds after turning on wifi.
Fix: (Workaround) Possibly affected by APs that allow TKIP encryption method. Reports of only allowing AES/CMAK helping. TKIP has known vulnerabilities, but older devices may still require it be enabled.
--------------------------------------------------------
Wifi connection issues: Wifi seems to go dead 1-3 times a day. Wireless still shows a strong connection, but no data actually passes (SMS still works).
Fix: (Workaround) toggle wifi
--------------------------------------------------------
Poor 5G performance (T-Mobile): While this could be a T-Mobile issue, as they seem to have turned on 5G over most of our area using UHF bands (300mhz to 3ghz), performance is pretty choppy. Uploads seem to be more negatively affected, with speeds less than 1mbps at times. Download speeds can be up to LTE speeds, but often are not, and are almost always jumpy and not smooth during speed tests.
Fix: None, unless there's a way to disable 5G for now (if that would even help).
--------------------------------------------------------
Occasion outbound call issue: Sometimes making an outgoing call takes 2 or 3 tries. I can't remember the error, off the top of my head, but it's something like "service not available".
Click to expand...
Click to collapse
My wife and I have similar problems with mobile data and wifi both occasionally showing strong signals but requiring a toggle off and back on before data passage resumes. Both OP8P and OP8. Verizon for carrier.

Well, I guess it's good to know it's happening on Verizon too?
Seriously, this needs to be fixed. If it was just one carrier, I could see it getting out the door. But more than one (very different kinds) of carriers is pretty ridiculous.

Issue: can ONLY receive MMS on WiFi calling not on mobile data, SMS not effected.
More details in my thread here: https://forum.xda-developers.com/oneplus-8-pro/help/receive-mms-wifi-calling-tmobile-t4088673
Fix: use 3rd party SMS app, revoke all permissions from stock app, disable stock app

Updated OP.

I've found that disabling Voice over Wifi altogether seems to help with the MMS while on wifi issues. I still get a few that don't go through and have to shut off wifi altogether, but it's much... much better.
I'm wondering if this is also connected to my outgoing call issues. I'll be testing that also.
**EDIT**
While I still think disabling VoWiFi helps, it is still very much a crapshoot whether or not an MMS message will send or receive. Between this and the dual sim issues, I may need to see if OP will let me return this.

No idea if it's related but in comparison to EE, three is absolutely crap. Truly a horrific network, 50% of the coverage and 59% of the speed.
Have noticed that the phone aggressively tries to hand over to WiFi even when I'm not connected.
Removing 5G from the equation helps a lot, least in my instance.

dladz said:
No idea if it's related but in comparison to EE, three is absolutely crap. Truly a horrific network, 50% of the coverage and 59% of the speed.
Have noticed that the phone aggressively tries to hand over to WiFi even when I'm not connected.
Removing 5G from the equation helps a lot, least in my instance.
Click to expand...
Click to collapse
Curious, how are you seeing it's trying to hand over to wifi?
I'm so upset over this stuff. It would be more tolerable if OP had some sort of official status on some of these issues. Ignoring them won't make them go away.

Flapjack said:
Curious, how are you seeing it's trying to hand over to wifi?
I'm so upset over this stuff. It would be more tolerable if OP had some sort of official status on some of these issues. Ignoring them won't make them go away.
Click to expand...
Click to collapse
So it looks for WiFi constantly, also tries to switch between networks. You can disable it

dladz said:
So it looks for WiFi constantly, also tries to switch between networks. You can disable it
Click to expand...
Click to collapse
Are you talking about the "Scanning always available" setting? I already have that disabled. I seem to be ok with 5G lately. Pretty sure the bad upload speeds are just due to T-Mobile working out the bugs.

Flapjack said:
Are you talking about the "Scanning always available" setting? I already have that disabled. I seem to be ok with 5G lately. Pretty sure the bad upload speeds are just due to T-Mobile working out the bugs.
Click to expand...
Click to collapse
Then you're fine. Don't worry about it.

I thought I'd chime in a bit with T-Mobile 5G. Minus specialized cities featuring higher frequency 5G, T-Mobile nationwide works off of the 600Mhz band, AND REQUIRES the 1900Mhz or 2100Mhz 4G LTE band to properly function at this time. So if you experience poor 4G 1900 and 2100 frequency in your area, but strong 5G, it won't work well for you, and you are better off doing 4G LTE 600mhz instead.
Call your local rep and confirm the strength for those two frequencies for you. Just thought I'd chime in about the poor 5G performance nationwide for T-Mobile for some. Nothing to do with the phone exactly.

My OnePlus 8Pro sometimes disconnects several times a day the radio conection. It's hapend with LTE on Telekom. 5G is not available yet. It's happend also in places where I have very good LTE network coverage.
Restart the cell phone is the only option to reconnect.
Switching OFF/ON the Airplane-Mode, reset network settings or a Full Wipe bring no improvement.
I have already replaced the SIM card against a new one by my network provider (Telekom) to rule out a defect.
I also have no problems with my previous device.
So I'm currently using my old device in parallel with a Multi-Sim.
A network fault therefore can be ruled out 100%.
The latest software version has also been installed.
The crash normally occurs while surfing the LTE network and is noticeable that the Internet is unexpectedly no longer working. The Radio display on the phone show me a few minutes more that i have still connection to LTE and than it jump to "no network" as already described, "ONLY" restarting the device allows to log in to the network again.
It was also tried with intelligent network connection or two-channel download acceleration on and off.
With WiFi the internet works continuously.
The Device runs with Stock-Rom.
I also have contacted the OnePlus Support, but maybe someone here has a solution for me.
Many Thanks

Hofitown said:
My OnePlus 8Pro sometimes disconnects several times a day the radio conection. It's hapend with LTE on Telekom. 5G is not available yet. It's happend also in places where I have very good LTE network coverage.
Restart the cell phone is the only option to reconnect.
Switching OFF/ON the Airplane-Mode, reset network settings or a Full Wipe bring no improvement.
I have already replaced the SIM card against a new one by my network provider (Telekom) to rule out a defect.
I also have no problems with my previous device.
So I'm currently using my old device in parallel with a Multi-Sim.
A network fault therefore can be ruled out 100%.
The latest software version has also been installed.
The crash normally occurs while surfing the LTE network and is noticeable that the Internet is unexpectedly no longer working. The Radio display on the phone show me a few minutes more that i have still connection to LTE and than it jump to "no network" as already described, "ONLY" restarting the device allows to log in to the network again.
It was also tried with intelligent network connection or two-channel download acceleration on and off.
With WiFi the internet works continuously.
The Device runs with Stock-Rom.
I also have contacted the OnePlus Support, but maybe someone here has a solution for me.
Many Thanks
Click to expand...
Click to collapse
That is crazy. I think they may have fixed the wifi disconnects for me with the latest OTA, but when I did get them, toggling wifi worked for me. I never had to reboot over it. Your case definitely seems worse. Hopefully you don't have a hardware issue.

Hofitown said:
My OnePlus 8Pro sometimes disconnects several times a day the radio conection. It's hapend with LTE on Telekom. 5G is not available yet. It's happend also in places where I have very good LTE network coverage.
Restart the cell phone is the only option to reconnect.
Switching OFF/ON the Airplane-Mode, reset network settings or a Full Wipe bring no improvement.
I have already replaced the SIM card against a new one by my network provider (Telekom) to rule out a defect.
I also have no problems with my previous device.
So I'm currently using my old device in parallel with a Multi-Sim.
A network fault therefore can be ruled out 100%.
The latest software version has also been installed.
The crash normally occurs while surfing the LTE network and is noticeable that the Internet is unexpectedly no longer working. The Radio display on the phone show me a few minutes more that i have still connection to LTE and than it jump to "no network" as already described, "ONLY" restarting the device allows to log in to the network again.
It was also tried with intelligent network connection or two-channel download acceleration on and off.
With WiFi the internet works continuously.
The Device runs with Stock-Rom.
I also have contacted the OnePlus Support, but maybe someone here has a solution for me.
Many Thanks
Click to expand...
Click to collapse
I have exactly the same issue with the same carrier (Telekom Germany) with 2 SIM cards tested. Gotten worse with the 10.5.9 so I rolled back to 10.5.8 where the issue isn't happening that often. I haven't got this issue when enabling data on my secondary SIM (O2 Germany). I have also tested the new Android 11 beta where I got shortly disconnected from the mobile network and then the LTE+ logo changed to "g" and everything was fine again. The phone was still connected to LTE with full DL speed (did the whole initialisation with mobile data + 20gb music download). However the beta is not usable at this stage. Since I have an unlimited data plan on that Telekom Sim I cloud test the **** out of it and it seems that the disconnect happens when the phone tries to change or adds the cell connection while using data. I have sent OP the required logs and after that they ignored me.. hope they going to fix this as it seems to be a software/compatibility issue with that certain carrier. Also 10.5.9 isn't really coming to German devices with ota so they might know about that issues.

ch1llahh said:
I have exactly the same issue with the same carrier (Telekom Germany) with 2 SIM cards tested. Gotten worse with the 10.5.9 so I rolled back to 10.5.8 where the issue isn't happening that often. I haven't got this issue when enabling data on my secondary SIM (O2 Germany). I have also tested the new Android 11 beta where I got shortly disconnected from the mobile network and then the LTE+ logo changed to "g" and everything was fine again. The phone was still connected to LTE with full DL speed (did the whole initialisation with mobile data + 20gb music download). However the beta is not usable at this stage. Since I have an unlimited data plan on that Telekom Sim I cloud test the **** out of it and it seems that the disconnect happens when the phone tries to change or adds the cell connection while using data. I have sent OP the required logs and after that they ignored me.. hope they going to fix this as it seems to be a software/compatibility issue with that certain carrier. Also 10.5.9 isn't really coming to German devices with ota so they might know about that issues.
Click to expand...
Click to collapse
Thanks for the feedback.
That the Problem with 10.5.9 got worse i can confirm. I loaded this Version in Germany by using the Oxygen Updater. But that gives hope to me that it is really just a software issue and no defekt on the device. So I will not send the device to OP for an unnecessary repair in the hope that there will be fixd with an update soon.
On the Facebook Oneplus page I have already heard from some people they have exactly the same problem, all of them use the German Telekom network.
Hopefully you get right, with that presumption, that 10.5.9 isn't really coming on German devices because they know the problem. So the fix will come very fast.

Hofitown said:
Thanks for the feedback.
That the Problem with 10.5.9 got worse i can confirm. I loaded this Version in Germany by using the Oxygen Updater. But that gives hope to me that it is really just a software issue and no defekt on the device. So I will not send the device to OP for an unnecessary repair in the hope that there will be fixd with an update soon.
On the Facebook Oneplus page I have already heard from some people they have exactly the same problem, all of them use the German Telekom network.
Hopefully you get right, with that presumption, that 10.5.9 isn't really coming on German devices because they know the problem. So the fix will come very fast.
Click to expand...
Click to collapse
You guys haven't heard any buzz about 10.5.10 yet? I'm on 10.5.10 in the US, which I feel has been a lot more stable than the previous two versions (which had alternating issues for me).
The biggest issue affecting me remains the issues sending MMS while on wifi.

4G Calling/VoLTE and Wifi Calling stop working after moving between cell towers

After a phone restart, VoLTE/4G Calling and Wifi Calling work for a short period, then stops working, usually after moving around between mobile towers and/or wifi hotspots.
I find it happens whenever the device loses mobile signal, or when the device flips down to 3g and then back to 4g, 4g data service returns but both VoLTE calling and WiFi Calling remain disconnected despite being enabled in settings.
This happens on my primary SIM only. I have a second sim in my phone at the same time which works perfectly with both VoLTE and wifi calling. I upgraded from a Mi 9 phone which worked perfectly with both these SIM cards.
Looking at the device logs (With Logcat reader), I get lines like
QImsService] ImsServiceSub : [0] Permanent IWLAN reg failure (IKEv2 auth failure)
I also see
IKEV2ErrorReceiver] Canadian configure is not set, return
Other things I've tried:
Updating to the latest MIUI version (12.1.5.0)
Network settings reset
Only using the one sim
Removing the second SIM
Clearing all caches
Clearing caches and storage of things like CneApp, Carrier Services, Phone Services, Phone, anything carrier related
Resetting APNs, adding APNs with bearer set
Setting phone to prefer 4G/LTE (ie do not connect to 5G)
Removing my VPN, same problem with VPN installed or not installed.
Removing sim cards and leaving phone off for a while (an hour or so)
Getting a replacement SIM
I have not tried a factory reset yet, as I am not confident in being able to back up the phone fully and other threads with similar issues suggests that won't solve the problem.
One way I've managed to get it stable is to dial *#*#4636#*#*, go to phone and set preferred network type to "NR/LTE". The phone does not connect to 3G or below in this mode, and unfortunately this setting gets reset when the phone restarts.
At this point I think its a problem with the MIUI software version itself, or some firmware driver that comes with these versions of MIUI. I'm hoping MIUI 12.5 will fix it, but I'm wondering if anyone else has seen this issue or knows what else I can try.

Upgraded to 12.5.1.0(RJDEUXM) and the issue is still present, also tried asking my operator to completely reprovision the line with no luck.
I guess I'm stuck with this behaviour until I upgrade my phone

STEP #1) See if VOLTE works normal when switching towers with a different phone.
If it does then you can try the things below, if it doesnt maybe it might be the cellular carrier issue.
If other phones work find then please note that VoLTE mainly works on 4G LTE ... donest work on 2G or 3G and may or may not work on 5G depending on your carrier. Find out what NETWORK BAND your phone is using when VOLTE is working. You can use a app like
Network Cell Info Lite​Once you find out the band you can then use a script or use a app so it stays on that network BAND. A little more advance but it may also possibly be a DNS issue in the tables during the change of towers during the reprovisioning... you can try a script to flush the DNS and reload the tables when the network info changes or bind them statically for testing purposes.
Still doesnt work it may just be the firmware's modem issue with that phone in the way it handles re-provisioning process during cellular multiplex switching.

Question Mobile data interruptions on POCO F3 - is there any cure?

Hello, I tried searching on XDA and elsewhere but could not find an answer so I hoping to receive help by writing my issue here.
I have bought two POCO F3's 128GB & 256GB on Amazon & Aliexpress respectively.
They both have the same issue when using mobile data (4g) loading websites and doing voice & | video calls like FB messenger there are interruptions like for a second there is no sound or video freezes. It does not happen on wifi or other phones.
I tried resetting APN, selecting proffered network to LTE, rebooting, switching SIM slot, resetting wifi, mobile and bluetooth settings. Updated both phones to MIUI Global 12.5.1 still no luck.
Country Lithuania (EU) carrier TELE2
We really like the phones, but this is pretty annoying as we do a lot of video calls due to quarantine and what not.
Amazon suggested to replace the phone but seeing as two of them having the same issue it will most likely will not help.
Anyone experienced these issues and came up with solution?

From what u described, seems to me is a bandwidth/mobile data speed problem. Looks like is not enough bandwidth for video call to work properly. So, what is ur bandwidth provided by ISP? What mobile data plan had from ur telephony provider? Maybe ur mobile data signal is low in the place where u make the call from. It can be so many reasons for the issue u confront with, other than a problem with phone itself (a hardware/software issue).

you can also try the latest china stable firmware 12.5.4

Alin45 said:
From what u described, seems to me is a bandwidth/mobile data speed problem. Looks like is not enough bandwidth for video call to work properly. So, what is ur bandwidth provided by ISP? What mobile data plan had from ur telephony provider? Maybe ur mobile data signal is low in the place where u make the call from. It can be so many reasons for the issue u confront with, other than a problem with phone itself (a hardware/software issue).
Click to expand...
Click to collapse
Hi, ty for reply. That should not be an issue, reception is great and we tried it in multiple locations. Our previous devices Iphone 6s/ Poco F1 worked flawlesly with the same carier.
Here is speed test done on mobile data.

Any other ideas?

Found this thread here and I found a solution. Apparently there's an issue with network interruptions in general, especially on phone calls. This can be avoided by switching on VoLTE and WiFi-Calling. This is what I found out over time.
Here's the fun part though: Through a little bit of research this turned out to be a vodafone-problem. I am just guessing you guys will be either also on vodafone or on the corresponding bandwidth in your country.
It seems to be a bug in the F3, but also something that happens when VoLTE is not activated for your SIM card. The phone will try to use VoLTE and this connection will fail, forcing the connection to reset. It will be back in 10-20 seconds, but this is of course super annoying whenever a stable connection is needed (like phone calls...)
Enter *#*#86583#*#* (86583 = VOLTE on dialpad) on your phone. and it will give you a feedback that the carrier check has been disabled. Note that this doesn't mean that VoLTE has been disabled. Checking the network for the capability is disabled then, which makes the setting visible on the SIM card settings. Same works for VoWifi btw.
Try playing around with those settings and see if the connection drops persist. I have no logical explanation why this is happening because what I am telling you is obviously call-related - and I do realize that what you're describing is about the data connection. For me this was related however and solved my issue.
Possible solutions:
a) try to get your service provider to switch on VoLTE for you (this worked for me). You're going to need to call support for that. They will reset your SIM card in the process. Reboot your phone and be done with it.
b) If a) is not possible, deactivate VoLTE in the menu that you activated with the code above. If you're lucky, this will stop the phone from trying to get this type of connection working, even though it's not available. This is broken exception-handling on the phone's side and Xiaomi promised to fix it. They are aware of the bug (since Aug 20th btw) and promised to push a fix into the next MIUI release
c) play with the settings and try to get the phone to not use alternative protocols, just 3G and 4G, also deactivate Wifi-Calling.
Hope this information will help somebody. If all goes well, Xiaomi will fix it and this will behavior will be gone in the next release.

same issue for me with 12.5.7
data interruptions all the time and full signal loss
very disappointed with this device from the day i got it.

O thought I'm the only one facing this problem.
It's so annoying to get an interrupted connection in the middle of the game.

not only game, and calls, i have too much trouble to get throught a call.

Hello all,
i was also affected by a similar issue.
In my case the symptoms were:
On mobile data/5G some apps would be accessing the internet but others wont..
I was able to overcome this by resetting the access point settings and then applying the ones found here:
Cytamobile-Vodafone Cyprus APN Settings for Xiaomi Poco F3 GT - APN Settings
apn.how
I hope it helps...

My fix for this occasional issue is to set the phone to '3g' only in network settings, then flick it back to '5g'. It seems to be area specific for me. Very bizarre.

ntemis021 said:
not only game, and calls, i have too much trouble to get throught a call.
Click to expand...
Click to collapse
I have the same problem, it helps to have the settings volte and vowifi enabled. Sometimes it looks low cell signal and loosing the connection.
Has anyone return for service the device?

It looks like we still have this problem, my F3 modem is crashing every few hours especially when it switches bands, very annoying.

Magister54 said:
It looks like we still have this problem, my F3 modem is crashing every few hours especially when it switches bands, very annoying.
Click to expand...
Click to collapse
It really is! We need a bug bounty for this

Hey I ran into the same problem in Hungary Vodafone Poco F3, 14.07 MIUI
4g net is working flawlessly but
Network connection is lost when start dialing
Nobody can reach me on phone
Enter *#*#86583#*#* (86583 = VOLTE on dialpad)
VoLTE select option turn on/off
Enter *#*#869434#*#*
VoWiFi select option turn on/off
I tried to switch on/off both but no solution just yet
sby has answer for this?
Where should I post this problem to be solved?

I also have this problem and I am from Iran. My mobile ROM is the global version. It seems that this problem is caused by the Poco F3 mobile hardware itself. If anyone finds a solution, please let me know, thanks.

Question no internet connection when switching from 3G to 4G

hello everyone, im having an issue on my poco f3 it happens on both miui official, eu v13 & 14
like title says, whenever switching from 3g to 4g there is no internet connection and i have to turn airplane mode on and off for it to work again...
you can trigger this issue by going to settings and manually changing to 3g and then back to 4g, but it can also happen automatically if the signal is low...
does anyone else experience this issue? is there any fix for this?

Shala1122 said:
hello everyone, im having an issue on my poco f3 it happens on both miui official, eu v13 & 14
like title says, whenever switching from 3g to 4g there is no internet connection and i have to turn airplane mode on and off for it to work again...
you can trigger this issue by going to settings and manually changing to 3g and then back to 4g, but it can also happen automatically if the signal is low...
does anyone else experience this issue? is there any fix for this?
Click to expand...
Click to collapse
3 possible reasons:
1) When youre using 3g, your phone is connected to the best signal 3g tower nearby, switching to 4g makes your phone use the same tower (could be a low signal 4g). When you turn airplane mode on and off, the phone connects to the best signal 4g tower nearby.
2) Faulty SIM card
3) Phone faulty hardware

3zozHashim said:
3 possible reasons:
1) When youre using 3g, your phone is connected to the best signal 3g tower nearby, switching to 4g makes your phone use the same tower (could be a low signal 4g). When you turn airplane mode on and off, the phone connects to the best signal 4g tower nearby.
2) Faulty SIM card
3) Phone faulty hardware
Click to expand...
Click to collapse
Thank you for your comment.
I dont think the SIM is faulty simply because when i insert it to my redmi note 9s, this issue does not exist.
does your poco dont behave like this?

country carrier always helps , what bands ? phone version global? that helps , https://www.kimovil.com/en/frequency-checker/US/xiaomi-poco-f3

jefffrom said:
country carrier always helps , what bands ? phone version global? that helps , https://www.kimovil.com/en/frequency-checker/US/xiaomi-poco-f3
Click to expand...
Click to collapse
Israel, pelephone carrier. phone global version from official poco store on aliexpress
happend on stable eea miui 13 & 14 also on global 14 and xiaomi eu 13 & 14