Hi!
I have pretty much the same problem, which I’ve described in this thread: Sim card deactivates itself
I contacted support and did a hard reset as they suggested. I actually downgraded my operating system since the problems begun with the latest update. At first I didn’t install google services at all, to test if the problem is connected to that somehow, but since the phone was working fine, I installed it later and, one by one also installed my favorite apps.
The phone has been working fine for a couple of months, but now the problem is popping up again. I don’t think I have installed any new apps in a while, so I have no idea what’s causing the problem. The mobile network icon on the upper right corner seems fine and the only thing telling me I’m disconnected are friends and colleagues telling me their calls are going directly to voice mail, so I have to restart my phone several times a day just to be sure. Even switching to flight mode and back doesn’t always help.
I wouldn’t like to hard reset my phone regularly, so I’m hoping somebody finds a solution 