Router will not get IP from cable modem

Ok, here's the run-down. I have Comcast Cable with a Motorola SB5101 modem. Earlier today I was trying to get an online game to work and I enabled DMZ for like 5 minutes. It didn't help my problem, so I disabled it and my settings were as they were originally. This is the only setting I ever changed, and I set it right back. However, whatever change it made doesn't seem to have been reversed. I don't really know what DMZ means or does (and I guess it's irrelevant), but I can no longer connect to the Internet.

My computers can all see each other via my router (Linksys WRT54G with DD-WRT firmware), but none of them can connect to the Internet. Connecting a computer directly to the cable modem works like a charm.

My question is, how do I get my router to get an IP address from the cable modem? I've power-cycled and rebooted my computer, cable modem, and router until my head exploded, and the router still says WAN IP: 0.0.0.0. As I said, if I connect directly from PC > cable modem, I get a WAN IP and have full access to the Internet, but the router appears to not be getting an IP from the modem.

I have set the MAC address on the router to clone to the one on the modem, is that what I'm supposed to do? I get no connection through the router whether I clone my PC's MAC address or the cable modem's MAC address. Furthermore, if I am supposed to use the cable modem's MAC, should I use the one that says HFC MAC ID or the one that says USB CPE MAC ID? I am connected using ethernet, not USB, so I'd assume the first one, but I want to make sure.

It's really frustrating when something is working fine, and you change one little thing you think is harmless, change it back, and now it doesn't work. I've tried restoring the factory defaults and the router, and that didn't help either But that's it in a nutshell. I don't think I left anything relevant out. Any ideas? Thanks in advance for any help.

 

Ok, this doesn't really make sense to me, but I told the router to clone the MAC address printed on the label on the bottom of the router. So it's cloning it's on MAC address, and that works?? I don't get why, as I thought the router needed to have the modem's MAC address so the ISP would think it was still seeing the modem. Ah, oh well, it's working now!

 

Hi Askantik,
It may be likely that you are too far from the wireless router. Or.. try resetting the wireless router. And the cable modem works because it's connected to the computer via a modem. Lol.