cable modem not working with AirPort Extreme router
I have been using a Dlink DIR-655 wireless router connected to a Scientific Atlanta DCP2100 cable modem for some time now. Things were working reliably but I had problems with wireless range and speed.
Last week I tried replacing the router with a new Apple AirPort Extreme. The wireless works fine, but loses connection with the cable modem after a few minutes. I understand that I need to reset the cable modem after changing routers so I powered-down the cable modem for 15 seconds then powered up again. AirPort shows a "green light" and the internet works for a few minutes, but soon becomes not accessible.
Are there any special settings that I need to do for the AirPort Extreme to make it work with the Scientific Atlanta DCP2100 cable modem?