Good post but before people start spending hours trying to figure out wireless interference ...

Having spent time reading thru the forums about interference, I think it is best to validate that interference is the problem by doing a simple test. Take your residential gateway outside and connect it to the line that is coming into the house and connect your laptop to the box thru ethernet.  If it still doesn't work or it is still slow then intereference is not your problem. It is some setting in the AT&T network that no one knows that is the problem. Ok, I saw one post that said that their problem was resolved by some settings change on their network. I haven't been lucky so far ...