It seems to be an airplay related issue.
If I airplay to the pair, they will sometimes just disappear. From the sonos app, from the list of airplay audio sinks - just gone.
All my sonos products are wired: My Beam, both Ones - the Beam hasn’t had a single issue. The Pair of ones just sporadically decides that they’ve done their duty and patiently wait for me to crawl behind the cabinet to powercycle them. Without intervention, they reappear after about 5 minutes as unconfigured (?+R). If I wait for another ~10-20 minutes, they are back to normal.
I have looked at the support info on port 1400. Interestingly, the left One is completely unresponsive: pings time out, it’s naturally gone from the connection matrix. Any ideas what this could be? The logs say nothing.