Hi @Alexandre_2 

Welcome to the Sonos Community! And, apologies for the delay.

You might be streaming higher quality audio from Deezer than you are from Spotify, and if this the case, it’s likely that the explanation for the difference is performance is due to local interference near your speakers. I recommend a read of our reducing wireless interference help page to get you started, but if you are unable to spot an obvious source of interference to remove, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.

If you are playing to a group, it may help matters to start the group with a speaker that has a strong connection - either ethernet wired, or situated closest to the router.

I hope this helps.