This seems an ongoing problem that you haven't cured yet.
On trying to connect to Prime it says there is an internet connection problem. Netflix works fine and if I use a (borrowed) firestick that works too. Your suggestions to delete the app and reinstall or just reinstall won't work as the tv says you can't do this for built-in apps. YouTube is awash with answers to this problem some listing up to eight solutions to try, none of which, like your suggestions, work. I noticed someone from 12/2020 had a similar problem but had had no replies. Samsung what is going on. I like the TV and its contents but wouldn't recommend to anyone because of this problem.
TV is UE55AU9007K