I've just done all of what you have recommended, the issue persists. I can connect to Diabolos just not on my main character, but yes that is correct. I got about 3-4 hours of play in.
After getting to the Doman Enclave in MSQ was around the time I logged off and could not log back in.
I've submitted a bug request in game and tried to contact a GM to no avail. Patiently waiting to hear back. I will make a thread for the bug.

Thank you.