I get same problem. It's the servers guys. They can't handle the amount of people on them so they randomly boot some of us.
What amazes me here is that this BS has been going on pretty much since launch of the game. It's either the regular servers during the peak hours or when new content has been added (so more people login), or its the dungeon servers that lag so much you struggle to complete the dungeon due to AoEs and such.

This has been going on long enough SE! Where is that EU based data center we where promised??

I bet that the Japanese data center servers don't have these problems... (If you live in the area.)

We pay for this SE. Fix it, before people get enough and walk out on you.