Okay, the cable modem I was trying to set up with the DIR-615 is a Cisco DPC3825. When I Google it, I find out that this is not just a modem, but also a wireless router (although I saw no antennas on it). That means I don't even need the DIR-615. Would that be right? I'm downloading the manual for it now and researching any problems. Feel free to jump in if you have any hints.