None of those are first gen speakers.  They are all S2 compatible. 

Don’t Factory Reset any units without further consult. 

​@shleep 

Force close the app, then turn everything off (router and speakers). Leave five mins, then turn the router on, let it boot up fully, then turn the speakers on until they have a white light.

Then reopen the app and wait a minute of two. Hopefully they will all appear again. 

Also ensure you have the latest app updated, and also go to Settings - General Settings - System Updates - Check for Updates. 

(None of this may work if you factory reset the speakers, as you mentioned “only the SL can be set up”…?)

There’s always a chance that a new piece of electronic kit somewhere in your home, or at a neighbour’s, is causing wifi interference. Have you tried changing wifi channel? 

Thanks for the input … I’ve tried the WiFi reset and switching off the speakers and reconnecting. The speakers have previously been named and alarms for example, were set. Now they all appear as “not available”. But, in the play 3 the alarm actually goes off! I’m going to retry these steps a bit more and ask for more help with more details later. 
 

​@shleep 

So what are you asking about…

1. Alarms
2. Speakers not being recognize by the app

Glad to hear someone else is experiencing “glitchy” problems.  My newer equipment connects fine but my play1 speakers are problematic.  They always work fine except when I specifically want them on in that room.  Sometimes it takes multiple attempts to deselect and then reselect.  Sometimes I need to unplug and wait a minute.  This happens in both Wi-Fi and Ethernet.  I tried giving them a dedicated up. Nothing helps.  I thought about updating my speakers but since I already do 50% of my music as airplay, I’m slowly moving to other brand AirPlay speakers which are working fine. 

Seems a lot like wifi interference , either from an internal source, or more diabolically, an outside source. Although I suppose it could be a network issue, with speakers connecting to different mesh nodes, since you’re stating it is both wired and unwired. Not enough information, ​@Maddyindc , to be certain.

I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, they get sensitive about GDPR.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

What I’ve resorted to doing was to plug in just one of the play:1 into the Ethernet, then it all worked and synced and showed up again on my app!  I was also able to see the SL. 

​@Maddyindc you can try it out. 

Thanks!  I also have one of the pair of speakers hooked up via ethernet and then doing the other half of the stereo off of wireless.  I also tried having both hooked up via ethernet (can’t leave it that way without a lot more ethernet work) and haven’t seen much of a difference.  I have 3 Play 1 speakers, 2 One speakers, and an Amp.  Two of the Play 1 speakers have a different hardware # from the other other Play 1 speaker and will never update to the same firmware version (they are currently on 17.0 while all other equipment is on 17.1). The problem is only with the 2 Play1 speakers that are currently on 17.0 (though it has been a problem on previous firmware versions but I never paid enough attention to see if the firmware version was the same on all equipment) which is why I think it is an equipment/software issue of some kind.  I submitted information early on in the problem.  Had problems having SONOS get back to me and then played tag about getting back in touch and I just dropped it.

It didn’t occur to me to check too! But I just did and yes all of mine are on 17.1, even the “newer” SL. So I guess I’m lucky!  Perhaps it’s really the software update issue. Maybe give Sonos diagnostics one last shot? Good luck!