That suggests your Sonos app can’t find them on your network, but your Spotify app can.

Any idea how to rectify?

I’ve tried switching my wi fi on and off and the speakers but still saying not connected?

The app definitely still has issues.

Try force closing the app and reopening. 

If that doesn’t work (and it certainly could), I’d next try a network refresh. Unplug all Sonos devices from power, then power off your phone (and I mean power off, not just turn off the screen). While all those devices are powered down, reboot your router. Wait a couple of minutes for the router to reload everything, then power back on your phone. While that’s reconnecting, power back on your Sonos devices. Give them a couple of minutes to reboot and reconnect before testing.

If that doesn’t work, 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.