How do i (by 2 users)

Well fastest, quickest and dirtiest would be to get a network cable plug it into the back of the thompson router and DMZ the MAC address or IP address the Xbox pulls.

That's the fastest, quickest and dirtiest.

For reference on your router, look up DMZ in it's manual and follow the directions. Go into the Xbox and have it give you either the MAC address or the IP address it pulls. Enter that information in the DMZ and you should be set.

You didn't post a model number so best I could do is give general directions.