Hi @Moglet 

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

Do you only see this behaviour with Sky, or do you see it when using the TV’s in-built apps/channels too?

If the former, then the volume commands are likely coming from the Sky box. If the latter, then the volume commands could be coming from the TV.

If the Sky box is the cause, it’s possible that you could prevent the behaviour by adding a CEC-less Adaptor between the Sky box and the TV (though this would maybe prevent the Sky remote from controlling the volume, depending on how it is done). If the TV is the source of the volume changes, I’m not sure you will be able to do anything about it, unless there are TV settings that affect the behaviour - or unless you want to swap the TV for another, of course.

In either case, the speaker logs will report that a volume command came from HDMI-CEC (the protocol over which HDMI devices communicate with each other), rather than, say, a Sonos app or the touch controls. I can verify this if you recreate the issue and submit a support diagnostic - please let me know here when you have done so and I’ll take a look. Please don’t share the number given, however. Note that I can only tell if the command was CEC in nature, and not which device initiated it.

 I do notice that my Arc occasionally stays on Mute ( Green light ) when the TV is turned on.  Less frequently it shows a white light, but the volume is on 0.  Most of the time it works as expected.  TV is Sony eARC & cable box is Comcast.  Volume is controlled with Comcast remote.