Hi @KSH 

Welcome to the Sonos Community!

I recommend you first try a reboot - turn off (unplug) the Sonos One and your WiFi router. Once the router has been off for 30 seconds, turn it back on and only turn on your Sonos One once you see your phone has reconnected to WiFi - this usually takes 3-5 minutes. The Sonos app will not connect until the speaker shows a solid white light (or when the light goes off, if set to do so according to your preferences).

Try again, and if that hasn’t helped, please remove and re-add the YouTube Music service from Sonos:

Remove a music service account from Sonos

Add a music service to Sonos

Finally, if you’re still having trouble, I recommend you get in touch with our technical support team, who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.

I hope this helps.