How can I give unique names to the 2.4GHz and 5GHz bands on my new Xfinity modem/router?

Today I exchanged our old router for the new model at the Comcast store. Back home, I have gone through the setup steps and have it up and running. In my devices' WiFi settings I now only see the one network name, which is fine for most devices (computers, mobile devices, etc.). However, some devices will only connect to a 2.4GHz network. So to get those going I need to be able to have my iPhone selectively connect in its Settings to either the 5 or the 2.4 bands (like my previous modem allowed).

On my computer, I have logged into the Gateway as "admin" and there I do see the two bands. However the message indicates that I cannot change the Network Name there - I need to download the "Xfinity xFI app." See screeenshot.

Already things are going sideways - there is no "Xfinity xFI app" - the closest I can find is the Xfinity app in the IOS app store. Is that the one I need?

Assuming that's the app I need (??) I have it up an running on my iPhone. Now where in the app do I edit the name of the 2.4 band to make it unique?