Win10 defininatly has some issues. I posted here a few months ago that it is simply not enterprise ready.
If they right click on the computer in network and try to remote, does it fail? If it does and you click on the diagnose it will come back and say "missing protocols". Nothing wrong with the remote computer, it the local trying to remote. The only fix I know is to disable all AV programs (msconfig/startup and services) and boot from the WIN10 ISO and reinstall with the "Keep Files" option. There is a kink in the free upgrade with AV running.
I have not experienced any problems from booting from the WIN10 ISO and doing a fresh install and deleting the partition and recreate. I did however have a winsock with one of the fresh installs and had to rebuild it.