Networking – Configure DD-WRT router behind a Cisco cable modem


I have a Linksys WRT54GS router flashed with DD-WRT that I'm trying to get a connection on behind a Cisco DPC3010 cable modem. I can get a connection just fine when I plug my computer in directly into the modem, but when I plug the router into the modem, it refuses to deal the router an IP. My ISP is Cox, if that matters.

Here's the basic setup for my router right now:

WAN Connection Type

  • Automatic Configuration – DHCP
  • STP – Disable

Optional Settings
[all default]

  • Host and Domain name blank, and MTU on Auto

Network Setup [all default]

  • Local IP –
  • Subnet Mask –
  • Gateway –
  • Local DNS –
  • DHCP Type: DHCP Server
  • DHCP: enabled
  • Static DNS 1:
  • Static Dns 2:
  • Static Dns 2:

Things I've Tried:

  • MAC address cloning to have my router's MAC match my computer's MAC (My computer is capable of connecting to the cable modem just fine)

  • Using all kinds of different DNS servers. I doubt this would solve this kind of issue, though

  • Powering down both the router and modem, fully powering up the modem, and then powering up the router

  • The Cisco modem isn't a router and doesn't have any configuration utilities of any sort; just a page that displays basic information about the modem (MAC address, serial, etc)

  • Changing the WAN connection from DHCP to manually match the info that the modem deals to my computer. Here's the ipconfig for my computer connected to the modem:


I'm really not sure where to go from here. Any advice?

Best Answer

Most cable internet providers requires you to use the same MAC address used before.

Here are few steps that you can try:

  • Check if your WAN interface can negotiate DHCP configuration;
  • Try to use your computer's network configuration on WAN interface (IP address, subnet mask, default gateway and DNS);
  • Try to ping to internet IP address (e.g. default internet gateway and;
  • Check if DNS is resolving with: nslookup

If not, try all steps cloning your computer ethernet MAC address to router's WAN interface.