Many large organisations don't allow traffik on port 4780. But they allow it on 80. So to remotely administer your QlikView server, you easely change the admin port.
Open the C:\Program Files\QlikView\Mangement Service\QVManagementService.exe.config with an TextEditor. Look for the xml entity “QMSFrontendWebServicePort” which is set to 4780 and change this to 80.