I have seen this problem with a number of virtual machines. The VM hosting environment is running Hyper-V 2016 and Hyper-V 2012 R2. This issue happens on both versions of Hyper-V.
I run a variety of guest operating systems including Linux, but this problem is only affecting VMs that run Windows Server 2008 R2. I have a small group of remaining 2008 R2 guests scattered around the environment. The server freezes up and stop responding to ping and RDP requests. At the console, CTRL+ALT+DEL does not work. The only way I've been able to recover the VM is by performing a hard restart / power-cycle.
When I try to shutdown the VM, it will enter a "stopping critical" state and cause network interruption to all the other VMs on the same host. At this point it becomes impossible to get the VM back online until the original Hyper-V host is rebooted. Live migration will work for the other VMs on the host, but it will fail for the unresponsive 2008 R2 server.
I'm wondering if this is some kind of bug for 2008 R2 guests. It's been occurring randomly across multiple Hyper-V hosts.