Well, that's a terrific set of helpful responses for you to consider.
If
@fenderman hasn't already managed to sort out the problem for you with the remote support offer - I have a suggestion.
It may sound a bit daunting, but it's actually not too bad, with a little help from the forum.
When network devices start up, it's common for them to broadcast on the network for lots of reasons, and this is intended not just to provide useful info for other devices on the network, but also to solicit needed responses.
If a device wants to grab a specific IP address, it's common for it to check the slot isn't already occupied.
And a switched environment will send the broadcast packets to all active devices, unlike the usual action where a packet is only seen by the destination.
These broadcast packets can be captured by a network sniffer program, and the data studied for useful info.
So my suggestion (if you haven't already got the camera IP addresses figured out) is to install wireshark and capture the broadcasts that one of the cameras emits as it is powered on.
Here is a download link for the very popular wireshark - select the 32bit or 64bit version according to your Windows version :
Wireshark: The world's most popular network protocol analyzer
www.wireshark.org
The steps to take are as follows:
On the Windows PC, close down all programs, to avoid unwanted network traffic cluttering up the capture.
I'm assuming the PC can be on a wired connection as opposed to WiFi.
Start wireshark.
When it initialises, it will list the network interfaces found.
The one you need will most likely be labelled 'Local Area Connection' and should start showing a small activity graph beside it.
Click it once to highlight it.
Power down the camera of interest.
In wireshark, click once on the blue shark fin icon at the top left menu. This will start the capture.
Power on the camera.
Wait maybe a couple of minutes.
You will see the capture building up.
Click the red square that's next to the shark fin, to stop the capture.
Use 'File save as' to store the capture file on the PC.
Zip it up and attach here and we'll see if we can spot any packets originating from camera activity.
Good luck!