Help Setting Up AT&T Gateway with Netgear Nightawk C7800
I used to have COX internet where the coax cable was used, now that I have upgraded to AT&T Fiber internet, I had to use this modem and ethernet combo to my Router.
The problem that has been ripping my hair out is HOW to transmit signal from the GATEWAY to my ROUTER. I have enabled IP Passthrough, reset AND factory resent multiple times to no avail. The router simply could not get any downstream, and since there are no internet connection, I can't even use router login, the Nighthawk app or setting up WiFi through IP.
I used to have COX internet where the coax cable was used, now that I have upgraded to AT&T Fiber internet, I had to use this modem and ethernet combo to my Router.
This is classic "double NAT" territory.
Two routers on your network can cause headaches. For example, you can end up with local address problems. Among other things, the other router can misdirect addresses that the Netgear router usually handles, such as routerlogin.net or the usual IP address for a router, 192.168.1.1.
It may be possible to put the modem/router into modem only (bridge) mode and then to use the second device as the router. Sometimes it is easier to put the second router into AP mode. But that has its own drawbacks:
The bad news is that the C7800 is a cable modem/router. Unlike DSL modem/routers, these do not support AP mode. You may be stuffed.
While many questions about routers are generic and could be answered anywhere, some things need specialist knowledge.
You might get more help, and find earlier questions and answers specific to your device, in the appropriate section for your hardware. That's probably here:
