https://www.reddit.com/r/AndroidTV/comments/5xtiye/mi_box_usb_ethernet_dongle_testing/

search took me less than a minute to find your answer. It's not that hard.

Do a search, I've suggested one I've used before but don't know it off hand.

we just tested the UGREEN 3 Ports USB 3.0 Hub with 10/100/1000Mbps Gigabit Ethernet Network and it works great so far. https://www.amazon.com/UGREEN-1000Mbps-Gigabit-Ethernet-Network/dp/B00LLUEJFU

http://i.imgur.com/M6TX7XI.png here's the iperf test.. unfortunately we dont have a gigabit router to test it with that time.