I am also having the same LTE issue as others. we have two M3’s, my wife’s car (2018, LR, FSD, HW2.5->3 upgraded) did NOT have a problem with the 2020.16.2.1 update. My (2018, P3+, FSD, HW2.5->3 updated) Lost LTE connectivity.
I have tried all of the standard resets, restarts, etc. Finally...