Did you install the Windows app fresh from the Sonos website, or did you just update it? 

I agree, check for updates.

Fresh install from Sonos

Some suggestions:

• Restart the laptop. Most likely fix? 
• Ensure the Sonos system is visible on the phone app. 
  • If it is, go to Settings - General Settings - System Updates, and Check for Updates. Run any updates as directed. Quit and re-open the Windows app. See if that has helped.
• Check you’re on the same wifi band as your Sonos, if your wifi has two bands (2.4ghz and 5ghz). It sometimes shouldn’t make a difference but best to give that a check.
• Failing all of that:
  • Turn off the router, the speakers, and the laptop.
  • Wait five mins, then turn the router back on (let it fully boot up), then turn each speaker on one at a time (letting each boot up to white light before moving to the next speaker), and finally turn on your laptop and launch the Sonos app.

I see a brown Sonos logo in the top left corner of the app. Is this the S2 controller? The Ray only does S2.

Did the old, usual trick.

Turned everything off and back on again.

Problem solved, thanks for all the advice!