what do you mean by "does not fully see the VLM server"? Do you use a special port for the background process? You can change this setting in your VLM Settings. Please try to telnet from your client to your server over that port as well.
Here is a link to a KB Entry which might be also very helpfull.
I am having the same problem in that when I see the server it does not show one of my licenses at all and the machines are unable to check out any licenses. The volume installers are unable to contact the server at all. In my case it seems to be with every machine. I contacted NI tech support and they could recreate the problem but haven't come up with a solution yet.
My background port is 4637 and I can telnet to port 27000 but not 4637.
it you're not able to successfully telnet to port 4637 please make sure this port is not used by another programm (maybe "QualiSystems TestShell Suite Services") and that you made an exception in your firewall.