One or two devices have had an issue of crashing when connecting to some routers. You might be able to do some research combining the ideas of switching off WiFi as you leave and enter your home. In this testing report Testing Samsung A3 (2016) a3xelte January 2021 Oreo "dev" build, I did such experiments and found a “soft” technique for starting WiFi.
Not very practical in daily use, but might allow more organised collection of logcat.
Very interesting input from @christianrablay. If mobile connection might be the issue - is there any evidence that mobile data, is the issue. So, in this case, is the phone capable of running and working for extended periods if mobile data is off. One could further extend this research using no SIM card or a different SIM card. Just testing ideas to think about adding to the bug report!
The other approach is to think of the install method - was the phone fully “Xiaomi” updated before the /e/ install?
Bon chance