I have a Verizon Westell modem/router. I have a Linksys router plugged into it. I had a DMZ set to the linksys. I disabled it, and i have lost it on the network. The linksys is now set to DHCP, and it is on line. The IP of the router is now 192.168.1.18, and the gateway is 192.168.1.1. I cannot ping that address, and I cannot log on to the web portal on it. Pretty confused.
The problem is probably the Verizon and Linksys bits are both using the same subnet. With that happening, when you try to go to 192.168.1.1, it doesn't know where to go and is confused, so it errors out.
I've had this sort of problem before, years ago, when I had a wired router, then added a wireless onto it as a wireless access point. Basically, you have to make sure DHCP is turned off on one or both routers and set the linksys to something other than 192.168.1.x, such as 192.168.2.x