[2021] Problem with Passworded Games

I haven't seen other such reports.

We need to determine which of you two has the problem. Can he join other passworded games? Can anyone else join your passworded games?

What if he hosts a passworded game, can you join it?  

I understand that. I was hoping we could do some diagnostic tests to pin down where the problem might be. But if you don't want to do that, that's your right of course.