Try this - goto ‘Settings/App preferences’ and reset the S1 Sonos App. On reopening choose the option to connect to the ‘existing’ Sonos system and follow the onscreen prompts and sign into your Sonos account and see if that perhaps works for you.

Hi and thnks for getting back to me. When I go to my phone’s “Settings” and bring up Sonos S1 there is no option to “reset”. And when I open the S1 Controller App there also is no reset option. All I see now is “Set up a new Sonos system” or “Connect to an existing system”… both of which I’ve tried and get the same results that it can’t see any Sonos devices. 

Well you do need to follow the option to connect to the "existing” Sonos system - do not try to setup a new system at any stage.. otherwise you could end up losing your Sonos setup. 

Do you still have your old mobile phone and is that still working for you?

If it is then ensure your new mobile is connected to the same local WiFi access point as that old phone - you need to then use the App to connect to the existing Sonos system. If the new Android phone has any vpn/mac-spoofing/security software such as firewall/antivirus etc. then temporarily disable that to get the Sonos Software up and running.

Hi Ken… thanks so much for your help, kind of a good news/bad news deal. I was able to finally get the system to work with my desktop system, running Windows 10. Think I’ve got something hinky going on with my new phone, also having issues pairing with other devices. Cheers and thanks again!