I have a Samsung S21 Ultra 5G
I have a Unifi AP at home and probably have about 3 other androids and 2 iphones in the house. Evey time i make a change to the AP, the controller provisions the news settings to the AP, the AP then disconnects all WiFi devices then reconnects when the provisioning is complete. While all the other mobile devices reconnects to the AP the S21 Ultra does not, I even give it a few minutes but still does not reconnect, the error i get is "Couldn't authenticate connection". The only way back in now is to forget the network then re-enter the wifi password, I'll still receive the same error but then it reconnects. This happens every time I make a change to the AP.
Secondly the face recognition is awful, I tried changing the face picture many times at different times of the day with alternative looks, however, the S21 Ultra, majority of the times, does not recognise the face and even when it does it takes a long time, btw the camera lens are clean. My previous non Samsung android phone would recognise my face instantly and I never had any issues.
Reboot didn't do anything reset network setting did did work.
I think the real problem with the wifi could have been due to randomised mac address, it seems to connects but it still says unable to authenticate but connects anyway, it means there is still something.
I had Huawei Mate 20 Pro and I never had a face recognition problem. I've just bought this phone not long Im thinking about returning it, I don't think it's worth the money.