I was wondering if I could move my comcast modem into another room with only an existing cable connection without any extra hardware needed and then move it back into the original room. I was wondering because I want to access xbox live i another room.
It may work, but it depends on how the place is cabled. If multiple splitters are involved to get the cable where the xbox is, then you may have signal issues there. But you don't need any additional hardware to try it.
Power cycle all equipment, whenever you change the device that the modem is connected to.