i googled it but best i found was the 20 ft offical one, and that doesnt even reach the stairs,
see i know its possible to use non offical cables cause another friend of mine has one that works ( his brother got it from some collage )
and that cable goes up two floors.
the only thing i know is that normal ether net cables dont work, somthing to do with the cable working two way, im not sure, wont pretend im clued up.