upgraded gateway, but can’t see network

So, I just finished a long post only to have this site delete it because it had to refresh.  

Keeping this one short.  

I upgraded my gateway. I kept the same network name and password, but none of my devices can see the network.

 I rebooted the gateway, but that didn’t help.  I spent an hour on Xfinity’s site and only went in circles and nowhere useful. I have never understood how an ISP can have such a TERRIBLE website.