Nighthawk and Xfinity Modem- No Internet?

I just got a Nighthawk X6S AC4000 router to replace my aging Apple Airport Extreme network, Modem has been set correclty to bridge mode and the radio deactivated, and the Extreme has been our wifi router with some devices directly wired to it as well. I tried to replace the AE with the Nighthawk, but the router would not relay the internet signal. Devices coould connect to the Nighthawk via WiFi and I had one computer wired in with ethernet as well. No internet access either way. The internet light on the Nighhawk is white and stable, indicating successful internet connection, but it is not being passed on to any connected devices. I was able to directly plug a laptio into the modem and got internet instanly, so the modem is working fine. I was also able to reconnect the AE network and that router does fine.

I tried rebooting both the rouer and the modem severla times in different order. Sam issue. Cannot figure out what the problem.