Most of the time my Sonos Connect delivers Plex music content to my AV system perfectly however, periodically, even whilst playing Plex content, it simply stops and repostd that the content can no longer be found.
I have tried many things to sort this - rebooting the Connect, restarting the app, checking that Plex is still running OK (which it always is) and re-authorizing the Plex server to Sonos. Sometimes I thing the re-authorization works, but not always.
It is most infuriating as it seems to always fail just when we have visitors etc.