Just ran into an issue where some old Windows server 2008 installs were starting to pop up with could not reach key management server (KMS), and thus bouncing to not genuine. Spent some time searching around for fixes, including running slmgr, swapping out dns, etc. None of it worked.

Turned out the solution was actually easier:

The network driver upgrade will force a reboot. Once that’s done, the instance will be able to activate.