@Bingo66 Hello, 1. Try to reset network settings: go to Settings / General administration / Reset. Does the problem persist?
2. In case the first setup of your phone used a backup from another phone, it is very likely that you will have to perform Factory Reset again, and not use any backup-install everything from scratch.
I'm having the same problems with a S21 Ultra. I've tried all the same steps as instructed by Samsung with no success. I've sent a million reports via the members app but still no joy