Just had a similar problem, though it's a Netgear and they said it's a problem with the line (not my house). They were supposed to call me back 10 minutes ago to see how my speed was. I've dropped from 11meg to 7.5meg

I turned it off last night to come back to no internet for the whole day. No amber light or anything. It's working now but not chuffed about the drop in speed. Posting up a new thread with my problem though.

Router wouldn't even amber light this morning