Wireless constantly disconnects

My wireless connection constantly disconnects. The time it takes for each disconnect to occur varies between 5 seconds and about 10 minutes. Sometimes the only way to get it connected again is to reset the modem, sometimes if you just do nothing the connection comes back on it's own. The wireless connection is never steady for more than about 10 minutes during any time of the day. This is with all devices using wireless connections (3 different laptops, 3 different phones, PS3, etc). The Xbox 360 I have set up with a wired connection works fine and seems to never disconnect, same when I use a wired connection on my laptop (though it does seem to be slower than advertised). I'm at work at the moment, so all I can say now is that I have the high speed ultimate package with a Cisco modem (Dpq3925? not entirely sure on the model number, can update once I get home) and I am in the Newport News, VA area.