My phone (Xiaomi Redmi Note 10, Android 11) spontaneously disconnects from the mobile internet after being connected for a couple of hours, and it **won't** automatically reconnect. Can stay unconnected for however long. After I switch to the flight mode and back, it reconnects for some time, then loses connection again.

Is there any way to **diagnose** what is the problem? Maybe to find some **logs** from the network hardware.

I thought this might be due to a defective SIM card because the same problem happened to the phone it was previously installed in, but I had SIM card reissued at a mobile operator's office. The same problem is there with the new SIM card. What's the chance it's defective again? ¯\\\_(ツ)_/¯

**UPD 2:**

Turned out that 4g connection always disappeared during a call, and not just spontaneously as I originally thought.

**UPD 1:**

A little clarification: when internet is Ok the signal level has a 4g label, then in an hour or so the 4g label spontaneously disappears, and so does the internet connection. But the phone does calls and receives them. 

Thanks to Robert I managed to get logs by 
```
adb logcat -P "" # and then after waiting for the internet to vanish
adb logcat -b radio
```
A lot of messages say 2224 at the presumable time of failure such as
```[0]onDataSetupComplete: error apn=internet.tele2.ru, cause=2224, requestType=NORMAL```

[This][1] describes it as "SIM was marked by the network as invalid for the circuit and/or packet service domain." _How could this happen_ after sim worked fine for the previous 40 mins? _Is there anything I can do to prevent it?_


[Here][2] are the logs, but after seeing what a mess they are, I wouldn't expect anyone to look through them. But if you actually do, the logs start with turning the airplane mode on and off, then a lot of messages start at 22:31 (where the loss is probably is) then by 23:01 there is definitely no internet connection. 

Any help is much appreciated.

  [1]: https://developer.android.com/reference/android/telephony/DataFailCause?hl=ru
  [2]: https://drive.google.com/drive/folders/1-2TnQYbhzLucBQ_fhipbrUKNOOoiMr74?usp=sharing