I would try a reboot of your Router, iOS and web app are working for me in the UK

+1 that the desktop app isn’t working is a good indication it’s a local network issue and reboot should be first step. 

I had to use my sonos mobile app on iphone to re-authorise my turnein session via my mobile phone.

which is something I used to be able to do with the desktop app - but that’s broken now and so it seems that sonos (the company CEO - Patrick Spence) has decided that you must have a mobile phone to use your speakers.

I have rebooted my router/computer. Not a flex, but just for context, I have 20+ years IT support experience and use enterprise grade fibre network at home. It’s not a typical home-user issue.

Is the web app working for you now?

yep, the sonos mobile phone app needed to re-auth tunein and then it would work from the sonos web app.