I recently purchased a cisco 871 for use at home with a cox business line.
For initial setup/testing I had connected it to a linksys router but it would not receive an ip address. After beating my head against the wall for an hour, I read somewhere that dhcp will not work with a non-routable ip address on the wan link.
So I went ahead and plugged into my cable modem, and was able to pull an ip address from cox.
The problem is that after a random period of time it would stop routing traffic out the wan interface. All routes still showed up as they should, and I did not touch the config. A release/renew dhcp would fix the problem for another random amount of time (would pull same address).
I then brought it into work with me, and it will not pull a routable ip address from our campus dhcp server. debug dhcp revealed the following error which I was initially getting when hooked into the linksys:
"unknown dhcp problem.. no allocation possible"
if I assign a static ip address on wan interface, everything works fine.
i have also tried this with a completely clean config file (other than ip address dhcp entry on wan interface) with the same results.
linksys router worked with no problems.
any advice would be greatly appreciated.