I know what limitations are, so expect to get a message when I forward or reverse an UHD movie.
I get why it would get to you though, I would suggest an usb2gbit adapter then.
But make sure you get a good one, one that has been tested and has the closest to gbit throughput.
Have a look at this topic: Can anybody recommend a decent gigabit usb adaptor?
Or: Vero 4K USB->RJ45 adapter