super router?

So, after many calls to india, i was advised that my connection problem was due to not having a talk talk router!! Nearly fell of me seat..
Anyway my nice new super router arrived and for a week or so all was ok.
Suddenly although showing full signal upstairs (approx 2.5m directly above the router) i can not connect. Tried vatious devices with no joy.
Connection pretty good downstairs even through solid walls.
Any advice would be much appreciated.