Problem

I have a lab environment configured with 4 machines. It is running in Network Isolation, and has workflow and test capability enabled.  The testing capability fails only on one machine. 

Solution

Adjust the binding order of your network adapters so that external adapter is first.  To do this bring up the Network Connections window and click on the Advanced menu.  If the Advanced menu is not showing press the Alt key to display it.

From the Advanced Menu selected Advanced Settings.  The Advanced Setting dialog will open.

Use this dialog to move the external network adapter to the top of the list.

Explanation

If you are getting a message like the one below:

"The machine is not ready to run tests because of the following error: Unable to connect to the controller on '<TestControllerFQDN>:6901'. Reason: No such host is known. Make sure the test controller is online and the firewall on the test controller is not blocking the connection."

The chances are if you try to ping the Test Controller machine from the lab machine it will fail.  If the internal network adapter binds first it may cause issues when trying to resolve network names.  Simply move the external network adapter to the first position.