I Control volume over optical cable to soundbar
I do not use HDMI ARC. It was driving me crazy why I have two TLC Roku TVs, with external Rokus, with two Visio sound bars connected with optical cable. All the settings are identical on both TVs and external Rokus. One remote controls the volume on the sound bar… the other does not. The only difference is that the one that works is Roku Ultra and the other is Roku Ultra LT. I wish I could tell you more or explain it. Maybe someone else can. (The remotes that come with the TVs do not control the volume on the sound bar.)
I posted this because I just read many messages explaining why the above is impossible.