Have you tried getting the latest S1 update to the Play 3?

Sonos has some FAQ stuff that may help.

https://support.sonos.com/s/global-search/software%20update?language=en_US

If it is way behind sometimes you have to call Sonos so they can push you an update.

Odd, too. I’ve been running PLAY:3s on S2 since it was released. Had no issues in updating them, but that was way back in the day, haven’t done it recently, and things change. 

Wiring it to the router is a big help. Running the upgrade process from the S1 client is the way I went, but I suspect you could also factory reset them and just “add a device” from the S2 client, I would expect that might work.