Unable to connect to MKS: Failed to connect to server (IP Address) :902

So you’ve opened up the required ports 80 and 443 to connect remotely to your ESXI 5 Server with your Vsphere client and you can get to the ESXI Management Interface but when trying to open a Console session to one of your Virtual Machines you get the following error message:

The MKS in the error message stands for Mouse, Keyboard and Screen.

After a bit of research I have found that ports 902 and 903 TCP also needs to be opened to the ESXI 5 host for Console session to be reached. So make sure your Natting rules and Firewall reflect this.