Just flagging what I believe is a bug, using iOS app latest version (but this has existed for many months AFAICT).
I tried hardwiring one of my Five speakers at some point last year. I ran into issues, probably caused by a smart switch in dumb mode, and quickly gave up.
Since then, with no products hardwired, I have had the ability to edit SonosNet settings which according to the docs linked below shouldn’t be possible:
“If all your Sonos products connect to your WiFi network, the SonosNet Channel will appear grayed-out in the Sonos app and cannot be changed.”
https://support.sonos.com/en-us/article/change-your-sonos-system-s-wireless-channel
See screenshots below of persistent changes made to these settings:
