If "It's nearly perfect" , why are you here?

Yes there is a “fix” and it’s name is Gigabit LAN (1000M)

Fast Ethernet aka 100M is simply too slow once you start streaming high bit rate 4K content over SMB no matter how many workarounds you try .

This thread has a lot of info:

https://forum.kodi.tv/showthread.php?tid=332180