This is similar to another issue posted here. I have a Asus RT-N16 router that cannot get a DHCP address from my Motorola SB6120 modem (and Charter Cable) when the two devices are powered on simultaneously. Here's a list of things I have tried:
1. Resetting the Asus router to defaults — through the Tomato GUI (clearing NVRAM option) and the reset (WPS) button on the back of the router — many times
2. Powering off the Motorola SB6120 — many times
3. I've tried multiple versions of TomatoUSB — back to beta 10
4. Tried setting the hostname to something other than "unknown" under Basic —> Identification (see http://www.polarcloud.com/tomatofaq#why_cant_my_router_get_an_ip_a)
5. Disabled wireless radio, DHCP server, and anything else I could. Powered off and on the router and modem many times in different orders.
The router boots up and gets an IP address of 192.168.100.10 with a very short lease (< 1 minute). When that lease expires, it goes to the "Disconnected" state. Clicking on "Renew" causes it to sit with a status of "Renewing…" (and I've left it for an hour or so). Release/Renew doesn't help.
What does work…
If I plug in the cable modem and let it boot up fully (this takes 2+ minutes) and then power on the Asus router, it works. It seems to get a valid DHCP address the first time. The problem with this is that I don't leave my router and cable modem plugged in all the time for various reasons, so this isn't a good option.
What am I missing? I'm not a Linux expert, but I feel like I've tried all suggestions I can find on the web. Is it possible there is a bug in the DHCP code used?
My current configuration DOES work with DD-WRT — v24-sp2 (06/09/10) big - build 14584M. I sure would like to find a way to make this work with TomatoUSB though!
Thanks for all your work, teddy_b!