Deezer stopped working today

Your internal network is not the same as the external network and speed. Being on Fiber and stable defines the ability of the router to talk to the outside world, and has little impact on the ability of your Sonos speakers to communicate with your router. 

I would recommend an internal network refresh, to see if that solves any of your concerns. I would perform a Sonos network refresh, by unplugging your Sonos devices from power (or powering them off, if battery connected), and rebooting your router. Once the router has recovered, power back on your Sonos devices. This will give them both a fresh IP address, as well as a refresh of the Sonos OS. Finally, check your system for updates, in case there are any that need to be applied. 

However, if that fails to make a difference, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.

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

FWIW Deezer is working for me currently via Sonos, in the UK. 

Note, simply rebooting your internet doesn’t provide all the same value as the process I described.

On the other hand, I am glad you’ve cleared up your issue. 

Yeah, so explain to me how my I network speed prevent me from selecting something in the app.i could understand it could not play, but I could not browse. This app, while it has been better is still annoying. Like I have no speaker on my network and it takes Minutes to detect those.

Anyway, it is back now. So I guess this topic should be closed