I have a Yahoo-ATT DSL installation with 1 dynamic IP address. It uses an ISP supplied speedstream 4100 DSL modem. The 4100 appears to take care of all the PPOE duties and DHCP connections from PCs or low-end routers (I'm temporarily using a NetGear unit) work fine.
BUT, when I swap the Netgear out for my new 1811W, the cisco unit is unable to obtain a DHCP address from the modem. I can see the request on the modem lights when I do a "no shutdown fastethernet0"...but I never get an IP address.
The speedstream appears to support 100Mbps and I have tried 100, 10 and Auto on the 1811W. I can look at the log on the modem and it does not show any activity by the modem's dhcp service. However, when I swap back to the netgear unit, I can see appropriate entries in the modem log.
The 1811 is new and I strongly suspect its working ...I tested it on a different DSL line that had static IP. I see a number of similar issues in this forum; but have not seen any resolution that seems to fit my situation.
Any help/suggestions would be appreciated...my next step will be log the DHCP packets with a sniffer. I think I know what I"ll see...1811W DHCP broadcast...no response. But, that won't help me resolve the issue.