Have you checked the config.xml file? (C:\ProgramData\QlikTech\WebServer\config.xml)
There are some configuration options in there related to the tunnel.
I guess you are testing from the browser on the server since it says "localhost" in the error message. If not that might be a related to your error.
I got the same error message as you. But my problem was fixed by allowing the qvstunnel.dll in the isapi/cgi restrictions.