Quick and dirty answer – Windows Updates relating to CredSSP updates for CVE-2018-0886
The fun story time answer 
I’ve seen this one a few times now so thought it best to share with you all as many clients have gone around and around in circles with this one.
The typical story is usually after some sort of maintenance, update cycle, VMM server rebuild or (as was today’s case) an upgrade to SCVMM 1807… Upon restarting VMM many of the hosts go in to a Not Responding state.
This is quite a misleading error as more often than not, in recent times this has been down to Windows Updates.
Essentially, recent Windows Updates modified how CredSSP worked and many of the community met this face on by being unable to RDP.
The update changes the way CredSSP works and as you may/may not know, VMM heavily relies on CredSSP to function.
So, either uninstall the updates from the VMM server or Hyper-V hosts. Either way, both the VMM server/s and Hyper-V hosts all need to be re or post the CredSSP update.
Which specific update is it? Well, depending on the cumulative applied it could me a few. But essentially the specific update is this KB4093492 which contains the CredSSP updates for CVE-2018-0886
All cumulative updates March 2018 contain this update.
Pro tip: I’ve a stickler for keeping all my Hyper-V hosts and System Center Management servers on the exact same patch levels, and I suggest you try to follow this mantra as well… Especially if you’re thinking about S2D or SDN.
Hope this helps!
Dan