They self configure into a wireless network called sonosnet if they are wired together.

Indeed. There is a way[1] to connect to the individual sonos units and disable the radio entirely, but that certainly isn't the default.

[1]: https://bsteiner.info/articles/disabling-sonos-wifi

It's not just not the default. It's actually hard to find. You can't do that from the Sonos applications.

I agree. It seems pretty bonkers, but I'm sure some PM thought it would be great for some subset of customers to just be able to plug things in and have things "magically work". Anything beyond the most basic network though, and it really causes problems.

How do I switch that off then? I don't see any option in the windows sonos app's settings. I just see a Advanced Settings/General/Wireless Setup but that's to connect it to a wifi, which I do not want to do.