You don’t necessarily need to be a network guru to use Microsoft Network Monitor. I have used it more than a few times to troubleshoot client side applications that fail to connect to external resources for whatever reason. For example, a user unable to logon to a some external server, receiving the follow error: “The remote server returned an error: (502) Bade Gateway”
I tried the site myself with Netmon capturing a trace and saw the remote server was trying to establish a secure connection through a port other than common 443:
And here where printing from a remote app was failing to pass through our TMG proxy:
Windows Explored 