The virtual machine on Hyper-v takes a long time to load. How to diagnose what is the problem?

Question

Hyper-V

There is a server on it with windows 2016 standard installed and the hyper-v role. We have the only virtulka with a terminal server, also on windows 2016. And it takes a very long time to load, it can take 30 minutes, or maybe 3 hours. The download stops at the inscription Hyper-V and rotates the circle below. After booting, the system works correctly and there are no problems with it.