I can't figure out why my modem hates my router

I have a home network between my laptop and desktop, using a D-link 604 router, and an Arris TM402P Cable/VOIP Modem. I recently have upgraded my Comcast cable to include their VOIP phone service. When I did that, Comcast sent a guy to my house to set up this new modem, and some wiring for the phone lines.

When the new modem was set up, I noticed my internet speed dropped significantly, and speed tests show I now have a 1mbit downstream, compared to my old 6mbit, on BOTH computers, so that leaves the spyware/virus question out of the way. Certain downloads won't go past 90kb/sec, but on my old RCA modem I could always download at 600+kb/sec speeds. Swapping out the router proves that the modem works fine and my speeds are back up to 600+kb download speeds.

Now the tricky part - When I download torrents with lots of seeds, I was easily passing the 700kb/sec barrier. How is this possible? What is holding me back? Comcast cannot help me at all, I have called them three times, and they even sent a guy out here to take a look, and according to him the modem statistics were normal.

My only option right now is to unplug my router, but that leaves me with only one computer with internet and that can't stay that way. If anyone has any idea on what is going on, I would love to hear it.

Have you tried a router firmware update?

My parents had this same issue, but they lost their telephone. It turned out the modem was screwing up the guard bands so it would drop packets. The guy went through 3 different ones until he could find one that worked. Make sure it isn't just the router and call them asking for a refund!