It may be worth deleting the current alarm, and then setting up a new one, but if this behavior continues, the next time it plays the wrong station, I would recommend that you submit a system diagnostic within 10 minutes of the alarm going off, and call Sonos Support to discuss it when you’re awake enough. The diagnostic will capture the ‘state’ of your system at the moment you run it, you don’t need to call in within that 10 minute window ;)

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 phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

I have exactly the same problem on two different Sonos systems. I have set up both systems to play a specific radio channel via TuneIn on Alarm. But often Sonos plays a completely different radio channel than what it actually says it is playing? A bit annoying.

Have you submitted the diagnostic, and called in to Sonos, as I suggested? What feedback did they give you?