Just checked and Absolute Radio, Absolute Radio 90's are working (UK) on Tunein through the S1 App and on Alexa (Sonos Move).

Thanks for that, the problem must be on my side then. I will look into it further.

I've been getting a similar problem for a while now. Most mornings TuneIn won't play Absolute Radio, but I can play one of the other Absolute Radio decade stations. If I try again a little later, Absolute Radio is available again. I've given up using it as a morning alarm - too unreliable.

Sounds like you have network issues that are causing interference when the speaker’s alarm is trying to reach out to grab the radio station’s stream, Have you contacted Sonos directly?

I don't think it's network issues. If I try manually to play Absolute Radio, I just get the TuneIn identity "dings", but I then try Absolute Radio 60s and it's fine. Another day, Absolute Radio might work, and Absolute Radio 60s won't. A few months ago Absolute were sending a message at the start of each session saying that the stations would no longer be available on TuneIn after a certain date. They don't seem to have followed through on that, yet, but the problems started about that time.