Hi @Benkenobi90.

Welcome, thank you for reaching out to Sonos Community and providing a clear explanation of the issue your having.

To fix this once the speaker is connected to the ethernet cable, You need to set up the speaker wirelessly again Go to Settings » System » Network » Wireless Setup.

You can check this link also Reduce wireless interference this might be the reason some of your speakers are offline since theirs no changes in your wifi a presume?

Let us know if it works. If you need help with any other information, please be sure to let us know.

Hi Mark

I have another issue that is still a mystery

When i try to do what you asked me my app doesn't manage to connect to wifi

And it's really strange because my one SL is working on wifi…

I've already reboot my internet box...

Hi @Benkenobi90.

Welcome, thank you for reaching back to Sonos Community.

I suggest to factory data reset the missing speakers and after that hardwire the speakers again using an ethernet cable and on the Sonos app go to Settings» System» add product.

Let us know if it works. If you need help with any other information, please be sure to let us know.

It works !

Thank you so much for your help !

Have a nice evening

Hi @Benkenobi90.

Welcome, thank you for reaching back to Sonos Community.

Glad we managed to figure out the missing piece of the puzzle.

If you need help with any other information, please be sure to let us know.