Xfinity xFi app can’t reach my gateway to install Wifi extenders

I’m trying to install some Xfinity WiFi extenders (XE1-S). Installation is driven through the Xfinity xFi app. After login in the app, it says “Settings currently unavailable” and offers “Activate a new Gateway”. If I try activate and re-enter the network name and password, the app says “Getting Ready for Setup”, then “Please Try Again – Sorry, this is taking longer than expected”.

Interestingly, when I open the Xfinity My Account app, click internet, and then voice and data modem, it says “Something went wrong – We were unable to load WiFi hot spot settings”, but it does show the correct serial number and model.

I have deleted and re-installed both apps numerous times.

I have an Arris TG1682G modem/router with internet and phone services which both work fine.

How can I get the Xfinity xFi app to see my gateway?

Can I install the extenders without using the xFi app?

Help