I'm trying to save what's left of a CCTV network in my friend's pub/motel.
It's been bought with no documentation of the network, I've spent the last couple of days trying to figure it out with help from the AI.

Everything needs to work fine, but if those last 3 cameras aren't connecting! If I can't get them to work he's probably going to buy a whole new system and I think it's such a waste.

Here's what I figured out so far:

Equipment

NVR

• Dahua DHI-NVR4208-8P-4KS2
• Originally firmware 3.215.0000000.4 (2018)
• Upgraded to 2021 firmware, then latest 2024 firmware

Cameras

• Dahua IPC-HDW4631C-A
• Firmware: 2.460.0000000.16.R (2017)
• All cameras report the same firmware version.

Symptoms

One camera (105) works perfectly.

Two cameras (107 and 108) do not.

The NVR reports:

>

However, that error doesn't make sense because the cameras are definitely reachable.

What I've verified

• Cameras boot normally.
• PoE power is good.
• Ethernet cables tested and swapped.
• Multiple PoE ports tested.
• Cameras work perfectly when connected directly to a laptop.
• Can browse to their web interface.
• Live video works.
• ConfigTool detects them.
• Passwords can be changed.
• IP addresses can be changed.
• ONVIF enabled.
• ONVIF admin user exists.
• HTTP 80
• TCP 37777
• RTSP 554
• Encoding tested (H.264/H.265)
• Factory reset performed on cameras.
• NVR firmware updated to latest.

Interesting behaviour

After updating the NVR firmware, camera 107 suddenly behaved differently.

When plugged into the NVR:

• the NVR detected it
• prompted me to replace an existing channel
• automatically changed its IP from 10.1.1.107 to 10.1.1.66
• briefly displayed live video
• then eventually dropped again to:

>

If I unplug the camera and connect it to my laptop:

• it is indeed now at 10.1.1.66
• I can still access it
• live video works
• everything looks normal

So the NVR definitely communicated with it successfully.

Even stranger

Camera 108 previously behaved similarly.

The NVR automatically changed its IP to 10.1.1.72.

Again, the camera remained fully accessible directly from a laptop afterwards.

Cameras

Working camera:

Serial:
4L00F0CPAG6518C

Failing cameras:

4H07D26PAA56BAE

4H07D26PAA55C9A

Not sure whether that's relevant (hardware revision?).

My current theory

At this point I no longer think this is:

• networking
• PoE
• cables
• passwords
• ONVIF
• ports
• firmware mismatch
• video encoding

The NVR clearly discovers the cameras, authenticates to them and even changes their IP addresses.

It just eventually refuses to stream them and falls back to "Cannot find network host."

Has anyone seen this behaviour before?

Could this be:

• camera hardware revision incompatibility?
• corrupted camera registration database?
• Dahua private protocol issue?
• something else I'm completely missing?

I'd really appreciate any ideas. I'm happy to run any CLI tests, Wireshark captures, or hidden Dahua diagnostics if someone knows where to look.

Visual representation here >>> https://imgur.com/a/qkiyAQz