Could you maybe shed some light on your set up? What TV (make and model number)? What settopbox? What sound settings on TV and settop box? What Sonos soundbar? Connected to the TV in what way? What does the Sonos app say itis playing when you do/don’t get surround?

The audio you hear from the rear surround speakers are dependent on the type of audio you are receiving. If your source isn’t mixed in 5.1 surround and is only in 2.0 stereo, the audio from the rear speakers will oftentimes be very quiet or non-existent. With some stereo content, the Arc will perform an audio up-mix of the stereo signal to create a simulated surround sound. This means you’ll still hear most audio out of the front channels, but the rear left and right speakers will play what is determined to be ambient audio.

If you want the full 5.1 surround experience, you need to look for content that is mixed in a surround format like Dolby Digital 5.1, Dolby Digital Plus, Dolby Atmos, or multichannel LPCM (if your TV or media device supports it).

So, if commercials are giving you surround, but the ‘show’ itself isn’t, which I think is what you’re saying, that suggests the ‘show’ is in stereo only, and isn’t carrying any information on the surround channel.

But I’m not completely sure that’s what you’re saying, either. What source are you testing with, I.e. what channel, what movie? When you’re testing, open up the controller and then go to Settings > About my system. Look on the line for Audio input: under the main bar and tell us what that says.

Also, can you be more specific about which ‘main bar’ you’re using? Sonos has made the PLAYBAR, the PLAYBASE, the Beam, and the Arc. It might help troubleshoot if we were certain which one was in use. 

I am also mildly concerned about the statement ‘sometimes will be on but extremely quiet and distorted”. When that is happening, could you submit a system diagnostic , and call Sonos Support to discuss it? In general, that data is digital, so it should either play, or not. Sounding distorted could possibly a signature of wifi interference , but it’s unlikely. Not impossible, mind you, which is why the hard data in the diagnostic would go miles in helping track it down.

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