Power down all your S2 devices, and force kill the S2 app.

Now run the S1 app - it will only find your S1 Connect and will let you set it up.

Once done, power up the S2 devices and you will have a split system, ie use both apps, or use 3rd party apps that can handle split systems directly.

Check the C:A is older than 2015 from the start of the serial number on the device which will show the year and month of manufacture.

I would then remove/uninstall the S2 controller App from your mobile device and for good measure power off your S2 products. (The removal of the S2 App is the important step).

Install the S1 App and then try installing the C:A again (from factory reset, if required).

Hopefully that should work, but only if the C:A is S1 compatible only (older than 2015, generally speaking).

Then power back on the S2 devices and reinstall S2 App and connect it to the existing S2 system.

Ah I now see controlav has beat me to it.

Thanks for that guys. I’ve done as you suggested, but now I’ve re installed S2, it now says “amp is incompatible” and my option to click on ‘system’ isn’t available. At the top of my iPhone screen though, it picked up my Sonos One but I’ll attach what it said next as an image;

Just ‘reset’ your S2 App (Settings/App Preferences) and give it another go.. I think you needed to give your S2 system time to settle after powering it back on. My guess is it will detect the S2 setup next time you launch the App and will invite you to press the ‘join’ button on one of the S2 devices.

Reset my S2 app and this is what I get;

I can’t find the amp on airplay, nor can I play anything using the s1 app. 
 

Do you perhaps have multiple WiFi access points in your Home network? I’m thinking there is an issue somewhere with your system (SSDP multicast) device discovery on your network. Anyhow, it seems the obvious next step is to get your S2 App to see your S2 system.

The way to go is to switch off the S1 device, then go onto try to get your S2 controller to see your S2 setup - if there are multiple WiFi access points try to get your mobile to switch to the other access point (if relevant here) by standing nearer to it and switching off/on the network connection on your mobile.

I think it’s because the connect amp is too old so un supported now?

All Sonos Connect Amps are still supported by the S1 App - but I thought you had it setup in the S1 controller App already and was now looking to reinstate your S2 App/devices?

It could be though, that if the C:A has not been updated for quite a while, then you ‘might’ need the help of Sonos support to get it onto the latest firmware (if it’s not been used for a long time), but perhaps try it wired to your router, as that can sometimes help with getting firmware updates? 

The above screenshots in your later posts by the way are from the S2 App - you can’t setup a Connect:Amp on an S1 Household whilst you have the S2 App installed on your mobile device? (As mentioned earlier in this thread).

Can I just check the taken steps with you once again please…

You needed to…

• Power off your S2 Sonos devices and (importantly) remove the (gold icon) S2 controller App
• Install the (black icon) S1 App and create a new Sonos system with your C:A (from factory reset state) it has to have been manufactured (generally speaking) before 2015 to setup an S1 Household. 
• When the S1 system is all setup then power on your S2 Speakers and let them connect and settle.
• Install (gold icon) S2 App and connect to the ‘existing system’ and when it prompts you select the ‘join’ button on one of your S2 speakers.

ok, maybe I got some of those steps wrong. 
 

When I deleted S2, I did factory reset on the C:A, connected it on S1, but I logged in using my user name on the S1 app? Was that wrong to do?

No that’s absolutely fine - use the exact same Sonos account/credentials for both your S1 and S2 systems.

I’ll try it again now

Ok, so I’ve done all of the above. I currently only have the C:A on my S1 app, but I can’t play anything or see it on air play at this stage. 
 

is that correct?

That’s correct, the C:A is not an Airplay compatible device - but you can hopefully play to it though using the S1 Sonos App - Yes?

Note however, you could of course go onto add an Airplay compatible Sonos Speaker to your S1 Household, like a Sonos One for example (not a One-SL) and then Airplay to that speaker and group it with the C:A via the S1 App. That will play the Airplay audio to both devices.

It won’t let me play anything through the S1 app. It won’t even let me search for an artist/song/genre etc. 
 

I’ve just tried searching for ‘other products’ on the S1 app but it isn’t picking up any of my S2 devices through the s1 app?

proper head ache this one seems to be! 

Update, I now have sound from the C:A using one of the Sonos radio station apps 

My other Sonos products are all Sonos One Gen 2’s 

You won’t find any

You won’t find any of your S2 products in the S1 App (that’s not how it works) - Now continue with the steps I posted earlier and power on your S2 speakers - let them settle - and then install the (gold icon) S2 Sonos App.. then continue with the steps outlined.

If you want an Airplay compatible product to work alongside your C:A you can use a Sonos One, as stated (any generation - just not the SL version).. but you can perhaps come back to that later.

Installed S2 app, clicked on the top of the screen where it said there was an existing Sonos system found, this is what I got (like initially)

Presumably you have powered on your S2 devices and let them settle and connect to the router - perhaps just power off the C:A for a moment and fully close (slide off screen) the S2 App and try it again - if the problem persists then reset the S2 App and give it another go. You should go onto see this;

Choose to join the existing system.