The AV8801 has HDMI 1.4 inputs/outputs and will pass some of the original 4K formats. A lot has changed since then and the 4K formats have gone through several iterations. You will need something that has HDMI 2.0 / HDCP 2.2 to make sure you support any of the current 4K standards.
You could try with AV8801, but there will be some 4K devices/formats that just don't work with it.