@Alexandre. See below

@Alexandre. Sigh! I don't know what is going on. I set up the first one no problem. The second one could not connect. The two additional nodes flashed yellow then red. I moved one node even closer to...

@Alexandre. Oh wow. So DON'T but the Xfinity modem/router into bridge mode? Won't the two routers fight?

@VCL My Xfinity combo modem/router has 4 Ethernet ports. How am I supposed to know which one will work? They are labeled 1 and 2 --one row for "phone symbol" and one row for "computers symbol". I saw...

@Alexandre. The app is wiped clean of my previous set-up. It doesn't see anything and prompts to start the set-up the again.

Excellent. Thank you!! I will reinstall the app and login with my same credentials as when I tried the first time and let you know.