I got booted from an unsync, solo instance of The Sirensong Sea. I don't remember what the error code was, but it was definitely 9000x.

The odd thing, however, was that there was no build-up to the disconnect. Usually when I get booted like that, there is some kind of lag or whatever building up to it. Sometimes, in severe cases, enemies and party members will just stop moving entirely while all I can do is move around without casting abilities.

Not this time, though. It went right from smooth gameplay to the error screen. I think it's a server issue.