My existing 3-product system using S2 dropped a Play1 and Beam, leaving only a Play1. This happened first on my iPhone and iPad, but later on my Mac. Brought back the Play1 by resetting it (plugging in while holding button), but later lost it again. I could not update, add products or find missing products despite rebooting those dropped, even resetting the products multiple times. No issues with firewall or WiFi.
The answer was to reboot all the products by unplugging them, even the one currently connected that was still working. Only then was the system able to find them and successfully update.
Not sure what the problem was, but might have been because on the iPad the S1 app was still open. Could SONOS comment? Thanks.