EDIT: To be perfectly clear, I am not asking for suggestions or solutions. I am almost 100% sure, that this issue is specifically for MiBox S and it has something to do with the device's network capabilities. It is basically a software bug, that I hope someone from Xiaomi might fix soon.

So here's the situation. I have Mi Box S connected to 5 GHz WiFi, with no obstacles in between the router and device (like 2 meters away from each other with nothing obstructing in the way). Then I have a PC, connected via cable and there I have some with VERY high quality video content. But not high enough so that network speed would bottleneck in theory, but it actually does. I cant stream them over on my TV. It plays like couple of seconds and then freezes, starts buffering and plays for a while again, and so on.

I'm talking about 4K HDR videos, with pretty high bitrates, like 20-60Mb/s video bitrates. I know that's high, but still, not even nearly close to my router speed limits. And I'm 100% sure that it is the MiBox's network problem, because those same files can easily be played using a USB drive (so the device has enough horsepower, so to speak, to actually render those videos without any issues).

Also, my friend has cheap-ass shit-brand android tv box. It's not even AndroidTV, it's just like Phone UI in landscape mode, scaled up to a TV screen size. But it has no issues of streaming in the same scenario. AND ALSO, I have no problems streaming same huge-ass files with phones on the same network. So it is definitely MiBox S's fault. I just want to talk about this issue, so that someone at Xiaomi might actually fix this in next software update.