The issue appears to be elsewhere rather than with Blizzard. And also seems to be cleared up now.
" The issues you are experiencing this morning appear to be completely unrelated to the realms, but rather the path between you and the realms.
Let's say you left your house to go to the grocery store, everything appears to be going smoothly until all of a sudden you come across construction blocking your path to the store leaving you stuck without directions to the store. Unfortunately, there are not always detour signs posted to help guide you along another route. I believe this is very similar to what each of you are experiencing, only you can't see the instruction and your connection is telling you the path is invalid.
Some players have had huge successes by flushing their DNS. In essence, this could create a new, alternate path that may not be effected by the construction a few blocks away from the grocery store. Regrettably, this will not guarantee success, but it's certainly worth a shot in the meantime.
To read more about how to flush your DNS and other troubleshooting steps that may remedy your connection woes, please review the following support article:
http://us.blizzard.com/support/article.x...
In the meantime, we'll keep you up to date with any information we're provided. Our realm technicians are aware of the issue and are in communication with various parties to get you back in game as quickly as possible.
Thank you all for your patience."