Things that can help with netinstall, put a switch between the computer and device to be installed, also disable all extra network/bridges/wireless interfaces on computer so there is only the one you want to use.
I've tried this and also doesn't work.
Netinstall can suck, and can be the actual PC's/Laptop network interface causing trouble in getting netinstall to work.
I'v found (sadly) sometimes I have been forced to use a usb to ethernet adaptorto get netinstall to work, after trying a dozen times on a specific pc or laptop.
Mby that's some solution.
But nevermind. Still have warranty. I'll try to push HW through it. Thanks for all hints.