YouTubeTV 5.1 audio sync issues

[Lemmy Lugosi]

As the title says: I am having ridiculous issues with my YouTubeTV audio syncing with the video. This is not your run-of-the-mill sync issue that is easily remedied with a flick of the wrist on the Sync button on the soundbar’s remote control. This is a system that I personally set up, and I have set up my own systems for many years; I am pretty certain that I have this all connected correctly, but I am open to any polite suggestions.
The sync issues do not occur when I am streaming from Netflix, Amazon Prime, HBO Max, etc, only with YouTubeTV. The video signal is getting processed and displayed via ARC cable/ARC input before the audio signal, for some ridiculous reason.
It’s been about 5 years, maybe longer, since I have updated the wi-fi setup in my home. Do you think that a new router and modem might help in this case?

I am at the end of my rope with this #%$&*!

Thank you for reading.