removed the app and installed an older version (16.1).
Things are stable again and I can go back to enjoying my fav stations on tunein.
I’ve locked the app in playstore so it doesn’t update automatically.
I’m guessing Sonos will lock out the old app from working at some point in the future.
 

Hi there I am experiencing the same thing but I cannot figure out how you fixed it.

I removed Tunein a few years back once I started hearing ads but my stations all seem to run through it and as of the last few days it keeps crashing and restarting.  I’d prefer not to use Tunein at all but it appears to be stuck.  I have been on hold with Sonos tech support waiting for them to answer for what is now 95 minutes.  I

I was thinking of going back to factory settings to start from scratch but thought I would check here first and saw this post.

Do you use an Android phone? If you use iOS/Apple you can’t go back to the previous app. With Android you can delete the Sonos app, then Google “Sonos version 16.1 app APK” and download it from a good APK site like APKMirror. Once downloaded, you can install it on your phone. This is the ‘old’ app. 

But if on iOS, you’ll need to wait. (But also check on the App Store that you have the very latest version of the app as there were TuneIn fixes I believe in recent updates.)

Ah I see.

I did end up connecting with technical support after an hour and a half wait (they are pretty busy).  They workshopped finding other services that supported the radio station I listen to and we found that this particular station just stops working after a while and then restarting.  Have never had this before so perhaps an issue with Tunein or somehow the station?  Tech support thought it might be my internet strength and asked me to try playing each speaker using an Ethernet cable which I was going to try until I realised that the problem was isolated to the Melbourne radio station 3RRR.  No other station stops working for me except my favourite.

If no other station shows this issue, it really points to the server your ‘favorite’ station uses to feed their data to TuneIn. You may want to contact this station directly, some of them are somewhat slim in terms of people monitoring and ‘fixing’ their issues. 

Of course the old sonos app no longer works. I was then back in the same boat with Tunein stations crashing constantly.
However, I have noticed something strange. After I uninstalled the Tunein standalon app, using Tunein in Sonos no longer crashes. Also, I no longer get ads.
Does the Sonos app somehow link to the standalone tunein app if it is installed? (on Android) - and connect via a different method if the tunein app is not installed?

ignore that about the ads - they are still there. But at least the crashing has stopped.