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New Member

Cisco 871w WAN connection problem

Perhaps one of you experts can assist me with this problem: I've configured my 871W to get the LAN and wireless working without any problems. However, I'm now having trouble getting my WAN connection working. I've configured the WAN interface with the IP address from the ISP. I have the NAT translation from to the first usable address in our IP block, which is changed here for security reasons). They have given us a "block" of IPs, which ranges from x.x.x.110 to x.x.x.114. The first, is our actual address, x.x.x.110. The second is their gateway, x.x.x.111, or (according to them), the address of their ADTRAN router device, which is in front of ours on the the way to the Internet. I called them, and they stated that they do not have a NAT firewall in place on their router, and they are "just handing off the address to us". The Cisco device will replace a Linksys WRT54GL, which has a staic WAN IP of, and is using a gateway of I'm not sure where to configure a gateway on the Cisco device, or if that's even possible. I asked the ISP if they have encountered a similar scenario, and they stated that most customers don't use sophisticted devices like Cisco, only devices like the Linksys router we currently have in place. They were little help except to clarify that they do not have a conflicting NAT in place on their router. I'm attaching my config. This was all done using the SDM. Any help is appreciated, thanks.

Hall of Fame Super Blue

Re: Cisco 871w WAN connection problem


I apprecaite you have changed the public IP address but .112 with a subnet mask makes the actual network address ie. it is not a useable IP address.

In addition if the ISP gateway was .111 this would be in a separate subnet.

I know you don't want to reveal your public IP addresses but could you confirm whether the last octet and subnet masks are representative of what you have on the router.

You do have a default route in your config ie.

ip route FastEthernet4

although a more effecient default route would be

ip route "ISP next hop address"



New Member

Re: Cisco 871w WAN connection problem

Yes, thanks for replying. The public IP given is not the actual, you are correct. Two other people have suggested the change:

ip route 209.168.233.XXX (next hop default gateway)

Do I need to get rid of the the "default-router" line in the config? Someone else suggested I do so.

New Member

Re: Cisco 871w WAN connection problem

Hey, Jon:

Your fix worked, thanks. I also had to delete the other route: