This device number is already occupied by a different monitor, please enter the URL of a different device for this monitor. Please use this URL only on one monitor at the same time. If this is the right monitor for this URL please follow these steps: 1) navigate to Devices 2) edit this device 3) press the button "Allow other device to use this URL" 4) refresh this page on this monitor/browser or restart the monitor
If this problem persists, make sure that your browser supports cookies and does not delete them upon restart.