There are few things to try out
Resetting network go to settings>general management>reset>reset network
Go to settings>connection>APN tap reset
Run phone diagnostics in Samsung members app should be able to test sim card
Try your sim in another device see if sim is faculty or your carrier has a issue
Can rry factory as last resort
I'll leave a Link to register so you can communicate here, As a guest account you can only post questions but can't reply.
https://forums.androidcentral.com/sh...d.php?t=409154