Replaced Modem No Internet Now on ORBK50

I am no longer able to get internet s through my ORBI RBK50 although my devices in my home can connect to the network. I very recently had to replace a bad modem I was renting from my ISP (Xfinity). I now have a Motorola MB7621 modem of my own that I have set up. I spent hours with Xfinity to confirm that internet service was being delivered correctly. I also have been able to use an Ethernet cable directly from the modem to my computer and successfully connected to the internet. I also contacted Motorola support to confirm that everything was configured correctly. I have performed numerous restarts and even done a factory reset on both the modem and the Orbi router but still have been uable to get internet connection through the router. I've tried replacing the Ethernet cable as well from the modem to the router but still nothing. At this point I'm lead to believe that the router is now the problem. Please advise.