Where things stand
Blizzard has acknowledged server problems in WoW: Forever that are affecting some players. After the first forum reply came an update at 11:15 pm PDT: the restarts to fix the issues are now imminent, and the maintenance should be short.
Both Blizzard statements follow in the original wording.
To implement fixes that should address stability issues, we will shutdown and restart the Beta in the next few minutes. The maintenance period should be very brief.
We’re tracking server issues that are affecting some Beta testers, and our fix for this will almost certainly result in restarting servers today. Thank you for these reports.
Original report: Wowhead