Tried the remove DTV, restart Roku, reinstall suggestion but after almost 2 weeks sound went low yesterday. I have it set to sound leveling and fixed by switching off and on.
More concerning, I've had past problems with speech out of sync and recently no sound (for days) on channel ABC (which is why I consider the first issue a minor inconvenience).
I have an old Ultra (maybe 2017-2018) connected to an LG OLED65CX. Internet tops out at 200 Mb/sec connected via ethernet but may be limited by ethernet port on Ultra. Connecting HDMI cable is high speed to support HDR10 @ 60 Hz. I also fiddled with subsampling to 4:2:2.
Perhaps my Ultra is too slow and limited by onboard memory? I recently found the HBO Max app on my LG and it works much better than the app on the Ultra (faster and doesn't exit after long session of title browsing). If DTV would come up with an app for my LG, I won't need my Roku.