I've had no issues with mine. I have slow internet (6mb average) and the wifi works fine for netflix, and am able to stream my plex on it with 1080p movies. I haven't messed with any 4k stuff though.

Mi wifi is 30Mbps / 5.0Ghz channel and I can stream 4k60fps youtube videos just fine.

I can get my max wifi (100Mbps) speed according to fast.com on mine. That's through 2 walls and about 40'.

Archer ac1900 router. Same speeds on my s8.

Mine is great. Seems better on the 2.4 Ghz wifi channel.

I use the xiaomi WiFi router next to the mi box and give me 60mb download (60mb is exactly the speed my provider give me)

Its more a question how good is your wifi network

A reasoned response it to try with your existing setup, after confirming you have optimized wifi environment. Fail-safe is be prepared to get usb/ethernet gizmo for mibox.

Noone can predict about your specific wifi conditions

In my own experience, I must say it's not exactly stellar.

awful. just today had to restart it because it dropped the signal while i watching something