I have one of those 4K TV's that does not support HDCP 2.2
This box, combined with a Chromecast Ultra works! When I connect to the Chromecast from Netflix, it now shows that I can stream in Ultra HD (you might need to upgrade your netflix plan).
Note, if you plan to plug this box in into a soundbar or home cinema system, make sure that system supports 4K, otherwise it will be reduced to FullHD.
I had to plug the box in into my TV directly.