Thanks @sunshdw .
For @bjesien ’s benefit:
My wireless network had no wi-fi extenders of plug-in units. Just a modem/router from the local ISP.
I don’t know if that is an actual proper wireless system but it met Sonos’ stated requirements.
I can’t comment on channel interference because I don’t know anything about it.
I would agree with sunshdw that Sonos is solid when done properly. But from what I’ve experienced and read (more than I ever cared to) it can be difficult to do it properly. To the extent that their tech support and message boards often cannot solve people’s problems. But then again, many of their customers, like me, are likely not particularly literate regarding wireless networks.
Anyway, my advice reflects my experience. If you are going to run multiple speakers/units in your system be prepared to wire at least a few of them to your router. That part is relatively easy. Run the ethernet cable between the router and the speaker. Doing that discretely can be a challenge. Once wired up, go to the system menu in the Sonos app. Select your device and then select disable wi-fi. Done.....well, as long as there isn’t a Sonos Boost in the system mucking things up. Good luck.