I’ve gotten disconnected twice yesterday after maintenance and the 2nd time I got the Error: WOW51900328 message. I’ve been stuck on logging in to game servers ever since and have tried every solution there is: flushing DNS, deleting Cache/WTF/Interface folders, complete delete & reinstall of Battle.net + WoW, Router reset, Event Viewer monitoring, Firewall / Antivirus settings, disabled every other applications.
I also can’t play any other Battle.net games anymore since that second disconnect.