Nighthawk r6900 connects but it says "without internet"?

[CaboFishDog]

I am connected to my modem in other room via dsl cable. It has worked for 4 years. Now it only connects without internet service. Appropriate lights are all white. None orange. Power, 2nd light, 2.4 & 5GHz are all lit white. The 2 far right lights are also white. Seems the same as it's always been? PLEASE HELP ME. I MUST BE TOO F'n STUPID!!????

The 1 WAS orange but no more!!!  All are white.

THANK YOU

[CaboFishDog]

This is a nighthawk r6900 router. Sorry. I was going to connect a bunch of pics.

[plemans]

What modem do you have? 
You say you're using DSL cable from modem to router? I question this a bit as the R6900 doesn't have any dsl ports. 

Do you mean you're using an ethernet cable between the 2? 

[CaboFishDog]

U r probably right. There's 4 ports in the infinitum modem, out, which I have a cable in port 3, running to the r6900.

I setup, plugged and played everything years ago.

Just stopped today.

[plemans]

What optimum modem is it? 

If it has 4x ports, it could a modem/router combo device and causing a double nat. 

A double nat happens when you cascade more than 1 router.
https://kb.netgear.com/30186/What-is-Double-NAT
Fixes? There’s 3 options but only use 1.
1. Put the modem/gateway in modem only/pass through mode. This disables its routing functions.
2. Leave the modem/gateway in router mode but put the Netgears IP address into its DMZ. This forwards the data to the netgear. You can either leave the modem/gateway’s wireless enabled or disabled. Just make sure its using a different wifi channel to prevent interference
3. Put the Netgear into access point mode. This disables its routing functions. Wifi/ethernet still works but it does disable some features.
https://kb.netgear.com/26765/Which-features-are-disabled-on-my-NETGEAR-router-when-it-is-set-to-AP-M...