I have installed Windows Server 2012 in a dedicated server, Using a VM I installed Windows 7, Everything is setup for the VM to access the internet. But I am unable to login by remote desktop connection into this VM/Windows 7 from an external network. I want someone to give me some insight about this. I was able to login using RDP using local network. But I want to access the VM using remote desktop connection "mstsc" is there any particular way to route to the VM. My client asked me for this requirement, can a dedicated server be split into many virtual Machines and be given remote desktop access.If this has to be achieved should both the physical server and VM run Windows Server?
Start out by checking your firewall settings. If you can RDP from the local network, but not an external one, you are likely being denied connectivity due to a NAT Traversal setting being enabled (this is default on RDP for server 2008+ I believe).
Open Windows Firewall, go to Advanced Settings, go to the Remote Desktop User Mode (TCP), and disable the rule that blocks Edge or NAT traversal.
Furthermore, if it's sitting behind a firewall or NAT router, then you'll have to do some port forwarding to make sure the traffic gets to the machine in question - this depends on how you have the Virtual Switch in Hyper-V enabled (If you're using Hyper-V, but from your question it seems you are...)