I have posted a similar question previously but thought it deserves follow up. I recently obtained a Roku Ultra to use with my existing LG TV and Samsung Soundbar. Several people have offered "fixes" for my issue. Unfortunately none have solved my issue. I was just informed by Roku Customer Support that Roku does NOT have the capability to work with a NON-ROKU soundbar. I also just tried to reset up my Roku Ultra device. During the setup I read a statement that basically said ROKU cannot work with with other soundbars. I replaced a Firestick remote which easily connected to my LG TV and Samsung Soundbar. I'm shocked Roku does not have this ability. How disappointing!!
It's not that the Soundbar is a non-Roku Soundbar why it doesn't work, the reason is your Soundbar is connected by optical cable, that's why it won't work. If it was connected via hdmi cable, a Roku remote would control the Tv volume by IR, and in turn the tv controls the Soundbar via CEC signal over the hdmi cable. Yes Firestick remotes can be programmed for audio devices directly, Roku remotes cannot.
It's not that the Soundbar is a non-Roku Soundbar why it doesn't work, the reason is your Soundbar is connected by optical cable, that's why it won't work. If it was connected via hdmi cable, a Roku remote would control the Tv volume by IR, and in turn the tv controls the Soundbar via CEC signal over the hdmi cable. Yes Firestick remotes can be programmed for audio devices directly, Roku remotes cannot.