I have a Comcast Business 12/2 line with a SMCD3G-CCR gateway, normally connected through a WNDR3300 running DD-WRT. I've been trying to get the DMZ working on both the gateway and router so that I can host a number of servers - mumble, ventrilo, source dedicated, apache, etc.
Unfortunately, the SMCD3G absolutely refuses to port forward or DMZ. I do not have a static IP from comcast and do not need one - the people connecting to my servers are friends who I can give my new IP to if needed.
I have tried port forwarding. I have tried DMZ. I currently just have my desktop hooked up to the gateway, with DMZ enabled for 10.1.10.10 - my computer. Regardless of this, all of my ports are closed. I called Comcast today, and the tech tried to both DMZ my computer and then put my router in bridge mode, with no success. He told me the only way to get this working was to purchase my own modem, and suggested a Motorola Surfboard. Understandably I'd like to avoid purchasing another modem.
Is there any way to get this gateway to DMZ OR port forward my PC? I don't care if I can't get the router DMZ'd, as I can set up my home network through the gateway instead, but this problem has been frustrating me for months.