You have added your device(s) to your XProtect® installation, but you are unable to see live video, and the recording server logs show the message "Unable to retrieve serial number". Essentially, there are two possible causes for this error. Either the device is not accessible on the network (or only intermittently accessible), or the recording server cannot authenticate the device using the stored username and password. The license scheme for XProtect® software requires that the recording server knows the MAC address (the serial number) of the device prior to requesting a video stream. The MAC is usually discovered using a specific HTTP GET request, which requires authentication. This process might fail if there is a network communication problem, if the device is not responding properly, or if the administrative credentials on the device have changed.
- Verify that you are able to ping the IP address of the camera (or hostname, if you have added the device using its hostname instead).
- Verify that the device functions correctly using the built-in web interface or vendor-supplied software.
- Verify that the device still uses the default administrative username. Has the password been changed? Verify which username is expected by Milestone Systems A/S by checking the Device Pack Release Notes available in the Downloads section of the Milestone website.
- Verify that the device is running a tested firmware version.
- Restart the device.
- Reset the device to factory default settings.
- Verify that the Windows Firewall is disabled or is configured with an exception for the Recording Server service.
- Check the network utilization. If it is 80% or more, you are likely to see occasional network communication problems.
In some cases, this may be due to an outdated or mismatched entry for the camera's MAC address in the surveillance system server's ARP table.
If this is suspected, try the following:
- On the recording server PC, open an elevated command prompt
- At the prompt, type:
ping <device IP address> and hit Enter
arp -a <device IP address> and hit Enter
(the latter command returns the MAC address of the camera, the former should (re)populate ARP tables on the server)
Now, compare the result of the ARP command with the MAC of the camera. If the MAC addresses do not match:
- Enter the command arp -d <device IP address>
- Verify that the command was successful by using arp -a <device IP address> again (*NO* MAC address should be returned at this point)
- Repopulate the server's ARP table again with arp -a <device IP address> (the correct MAC address for the device should display)