ARRIS Modem + D-Link router = no internet

Question

I have cable modem with an Arris modem and we tried to use our D-Link 2310 router but it doesn't work we can't get the net (I ain't using the wireless and don't care about it btw). I've changed the router twice and switched the modem once and it didn't change anything.

Plugged directly into my computer the modem provide internet just fine and my modem has been tested at a friend's place (who's with the same ISP) and it work perfectly.

I call D-Link they say that the problem is my modem, Videotron (my ISP) says that the problem is my router. They all evade their responsibilities and I really don't know what to do anymore. I've tried everything thing I found on the net but it doesn't help.