As per the object. Of course you need an internet connection to stream from Spotify Tidal etc, maybe even to set up the system the first time (not sure), but, once a system is set up, do you still need an internet connection in order to play files stored locally? By that I mean: when there is a wifi network but without internet access (so that devices on the network can talk to each other but not access the internet), can I play:
* files indexed by the Sonos app, and
* any music via an app that is not officially supported by Sonos, but which has been reported to work, e.g. Roon, Subsonic or other DLNA / UPNP solutions
I am confused because tech support has confirmed to me in writing that you absolutely and categorically need an internet connection, and pointed me to this page: https://support.sonos.com/s/article/126?language=eng
However, many users have reported a different experience, and say they can play local files without an internet connection. So what's the truth?
Do the non-officially supported apps (Roon, Subsonic, etc) work but Sonos doesn't say because, well, it doesn't support them?
How about the Sonos app itself?
The link I was given uses very ambiguous language about powerline adapters and wifi hotspots; basically Sonos doesn't recommend them because they can cause delays in accessing the internet, and Sonos doesn't want us to think the delays are its fault. Fair enough. But why on Earth would Sonos require an internet connection in order to play local files? I can't think of a good reason!
Chromecast requires a connection because it must download the player from the internet, so if the internet goes down while it's already playing you're fine, but if it's down before it starts playing, then no. But how about Sonos?
All of these are reports of users who can get Sonos to work without internet.
PS In case anyone is wondering, I am asking, despite the reports in the links above, because I want to understand if this is something which is officially supported or not.