We have a hyper-v host cluster with relatively new hardware. The hosts and the VMs on them all work good, except when I connect to any hyper-v host from another host in the same cluster (remotely using Hyper-V manager), sometimes displays red error (as in attached pic). We see this on different hosts at different times, and is occasional, i.e. it works by its own (nothing to do with any particular time of day or week). This cluster is in DMZ. And this does not seem to affect the working of virtuals or the host. We can connect to the host fine.
We had network guys take a thorough look in to this and they could not find anything. So Network seems OK. We do have few more clusters in non-DMZ zone, and these do not have such problem at all.