Have you checked to see if they’ve moved from TuneIn to one of the other radio streaming plugins? Probably the quickest way is to go to the Tunein website portal, and try playing the station there.
 

I’d also suggest rebooting your router, followed by rebooting the Sonos, on the offhand chance there’s been a DNS update that hasnt been carried properly through. 

As far as I can tell, the radio stream appears  broken.  I suggest you contact the station about this.

I had the same problem! Have you updated your Sonos system and app to the Sonos S2 versions? If so you also need to set up the Sonos Radio function. After I did that the TuneIn streaming started functioning properly, even though The Peak isn’t available over Sonos Radio.

Good luck… the station is great, and having it over Sonos really great.

Any help/suggestions for someone who can’t upgrade to Sonos S2 version?  I have a play 5 gen 1 which isn’t compatible with the new update.  S1 is supposed to continue support for streaming services, so I don’t understand why it won’t stream The Peak through tune in.  I find that other tune in stations still work, but the  Peak doesn’t.  Any help out ther would be greatly appreciated since this is my go to station.  Thanks in advance!

Have you tried the reboot process? S1 or S2 shouldn’t make any difference.

Unplug all Sonos devices, then reboot your router. When the router comes back up, plug back in your Sonos devices. Go into the Sonos controller and do a search for ‘the peak’, do not play it from a saved favorite.

It should play, I just tested the station through both TuneIn’s website, and through Sonos. 

Hold on. I was hearing the ‘ you’ve connected to TuneIn” feed on the Sonos, and not the station which was playing on TuneIn’s website. Which suggests an issue at the radio station. I suspect they use a different server to feed the Sonos stream than they do to stream the TineIn website stream, so they can more easily track users. Have you contacted either TuneIn (less likely to help) or the radio station directly (more likely to be able to help)?