I and a few guild mates have also been experiencing this issue recently. There have been other threads on this topic already, but to my knowledge nothing has been pinned down as an exact cause.
Some have blamed: Comcast, (which I also have) as far as i know its all conjecture and hypothesis. One might as well claim that Anet is reallocating servers for Alpha testing of GW2... but that would be a complete guess and horrible rumor /wink wink nudge nudge
Edit: Subject of post already exists some helpful info here:
http://www.guildwarsguru.com/forum/c...ml#post5449598