Hi @x-son, 

Thanks for reaching out to the Sonos community and for letting us know about your concern. Let me help you with this.

Upon checking your system from the link you provided, your Sonos is running under the S2 system (version: 12.2.2 build: 61183220). You may download the S2 app on your mobile device and connect to your existing system. Once you're connected, you can already add your other Sonos One SL. You can download the S2 app for your Mac computer on this link.

We understand that Creston's current line of panels unable to support the S2 system. Our only solution, if you wish to continue using Creston panels is to downgrade your Sonos system back to S1. You can downgrade your Sonos products to S1 if you have at least one Sonos product running in the S1 system. 

Factory resetting all Sonos products will set them back to default settings. However, it may no longer recognize the S1 system. You can try to set up your Sonos products back to S1 and you may start setting up with your Sonos Connect. If you set up your Sonos Connect successfully to the S1 system, then you can proceed with setting up your other speakers.

In any case, you encounter any issues during the setup, at this point, it would still best to contact our phone support since we can only guide you on basic troubleshooting with your devices.

Please feel free to reach out if you have further questions or concerns, we’ll be glad to assist you. 
 

@Rowena B. , would you be so kind as to confirm that you can still downgrade from S2 to S1 if you have an S1 unit to add the S2 device to? A rather well thought of forum member has said that this ‘back door’ for down grading was no longer a possibility, having tried it at length. Given that he writes his own software against the Sonos API, I’m inclined to believe him, although I have not tried this myself. 

I have been able to downgrade S2 speakers to S1 in the past by factory resetting them and adding them to an ‘existing’ S1 Household - the important thing is the S1HH must exist to do this.

However ...also note the recent message posted on the Sonos Status Page here:

https://status.sonos.com

Thanks. I’ve been trying to follow your instructions but unsuccessfully. I didn’t realise my system had been upgraded to S2. This is the problem with Sonos’s such aggressive push to get users to upgrade to S2 with constant messages in the app which cannot be turned off. One of the users must have clicked on the incessant message to upgrade the system, killing the system at the same time. 
 

I’ve tried following the instructions to downgrade the Sonia Connects to S1 via a factory reset, but this has failed. Although the Connect forgets all settings & connections, the operating system is still S2, just as @airgetlam has stated above.

We bought into the Sonia system because of the advertised partnership between Sonos & Crestron so it is very disappointing to have the system fail to work already. 

Oh man, thanks autocorrect. Everywhere I wrote “Sonia” above, just read it as “Sonos “.

The adds and the constant messages to "upgrade" to S2 are a real pain.

There should be an Administrator assigned to each Sonos system to allow or deny upgrades, not carte blanche for anyone with access..

Well, I had no luck with factory resetting devices trying to get them back to S1. I even removed them from the system to a new standalone unit and they still remained firmly stuck on S2.

Eventually, I managed to line up a phone call with a Sonos tech, who needed remote access to a computer on my Sonos network. Through this, he was able to send magic signals to the Sonos devices to force them to remain in the S1 path. My basic understanding is that my system now thinks that S1 is an upgrade over S2.

So, I then clicked Update in the Sonos S1 app & all my S2 devices “upgraded” to S1. What’s more, I won’t receive any more nagging to move to S2 because my system thinks that S1 is the latest & greatest. That’s fine for me because of our Crestron limitations preventing us from moving to S2.

All up, that’s a good outcome for me. My system works again, it won’t nag about upgrading & nobody can upgrade it accidentally by pressing the onscreen buttons. 

Sonos please fix this S1 / S2 debacle.  Single app please for S1 + S2 units, with two different groups of units. Make it easy for users to move S2 units to / out of S1 groups / modes.  Freeze S1, no new features, not even bug fixes.   S1 /  S2 do not have to interoperate in any way.   Focus on what your loyal customers need, in the long term it will result in more sales.

Ran into the same issue. Since today the sonos S1 app is not useable any more. I'm enforced to load the S2 app but I still have one device which is not compatible with S2. My ZP90 shows that it got kicked out of the sonos network. I can see every device but the ZP90 has no name and is shown as undefined.

I also guess someone has upgraded the system by accident. I used the ZP90 to stream to two sonos one boxes from my notebook that I grouped together. That was the only option to stream in stereo. This is now no longer working. And who pays for that now useless piece of hardware?