I experienced the very same problem. I went through the same procedures as you did, and it took me some time to solve it:
The ethernet adapter ind the NUC6I5SYH is the "Intel I219V Gigabit Ethernet LAN adapter". Yesterday Intel released the new driver-pack to the "Intel® Ethernet Connection I219-V", and you find it here: Intel® Ethernet Connection I219-V Specifications
I have used the latest version 20/7, and it solved the problems.
You're are probably aware of it, but download the driver, un-zip the compressed files, open the Windows Device manager and update the ethernet-driver pointing to the folder containing the downloaded driver.
Have fun - Trowin