Here is a more clear answer: it is recommend to always use FQDN for all server names including your vSphere client connection to your vCenter server and the vCenter server connection to each ESX(i) host. So proper DNS registration is required. vCenterServer and each ESXi host must have a FQDN A record established in your internal DNS servers. My vCenter is on a Windows server, so it was auto created. I manually added each ESX host with a FQDN A record.
I was having the same issue "Unable to connect to the MKS: Failed to connect to server" while connected to vCenter while using just the NETBIOS name. Realized I was using just the NETBIOS name for my vCenter server connection with the vSphere client. I already added the ESX server record in DNS and vCenter was connected to it using a FQDN. But since I was using only NETBIOS and a bad DNS server on my desktop computer, it apparently was unable to connect to the server name (either vCenter or the host) in order to launch a VM console screen. I tested using the vCenter server's IP only as suggested in other post, but that had the same failed results. It doesn't have anything to do with the port 902. Closed vSphere again and reconnected to vCenter using FQDN, opened a VM Console window, and worked perfectly.