Lots of confusion with 4K, HDCP , HDMI etc...
These two videos attempts to explain the different stuff :
and for Audio :
If you have old tech and some new tech (4K HDR), there may be compatibility problems..
HDFury seems to have a solution to solve this :
The Vertex seems good, but at US$299, its not a cheap solution.
https://www.avforums.com/review/hdfury-vertex-review.15094