Hello @PascalCanada , welcome to Sonos Community!

Please have a look at the below thread, you might find the information shared useful.

We are missing some valuable information such as the TV model for the right settings and the source of sound, be that an application, a 3rd party HDMI-connected device or a regular channel.

Make sure you have not disabled the Wi-Fi of your Sonos Arc via the Sonos App (gear icon at the bottom right → System → “Name of HT room" → Arc).

Have also a look at the following support article: Change surround audio settings.

I hope this helps, but feel free to reply with any further questions, if you have.

I have set the surround audio to 10, and set the distance to 2 to 10 feet (previously set at less than 2 feet).

And it works.

What I'm looking for is the airplay calibration, but I'm on android and this feature does not exist ( it's a shame). My room is high 11 feet and long by 9m and large by 5 meters. I don't think this system take that in account.

Also, should I add oneSL on the side of the tv?

Thanks for your support

You could certainly borrow a friend who has an iOS device to do the TruePlay, but it may not make a significant difference. In roughly half the ‘rooms’ I have, it seemed to make no difference at all, so I ended up turning it ‘off’ But if you’re not moving the speakers ever, doing it once allows you to toggle the feature, so you’d be fine doing it with a friends device once. 

Not sure what purpose the Sonos One SL would serve. It would be in another Sonos ‘room’ and be subject to the 75ms delay when grouped with the Arc, while the TV’s input was being played. It would be completely in sync while streaming music to both ‘rooms’

In my room, I have my 65" tv with Arc at the stand level and the sonos boomer at the right. In front of that, I have my couch and behind it, at the hedge, I have my Era300.

I want to get the Atmos effect, so that's why I'm asking if OneSL could help or not. I would put it on the sides on the Arc bar.

The Arc and Era 300s surrounds are already Atmos capable.  Adding the One SL will not add to that, because 1) A One SL has no Atmos capabilities and 2) It cannot be added to your room, you already have the soundbar, surrounds and subwoofer so your current room is maxed out (except for an addition Sub if your current is a Sub and not a Sub-Mini)

Ok thank you for your advice, very appreciated

I don't need another sub ( the actual is the big one). In tests I saw, there is no audible and meaningful plus value to add a second sub.

Cheers guys, and thanks again.