Dahua NVR Dropping Network Connection Every Second

We just installed a new Dahua NVR at a school.
The NVR loses its network connection every second or so when connected to the schools gigabit network.

We know its the NVR losing network connectivity because we can ping the NVR and see it dropping.

When we move the NVR and camera off the schools network and on to our own gigabit network the nvr and cameras work fine with no drops.

The strange thing is that when we put an OLD model of dahua NVR on the schools network...
It works FINE with no problems.

We have tried a couple of the new model NVR's and they both do the same thing.... dropping network connection every second or so...

Any suggestions?

A couple questions that may assist someone familiar with Dahua to answer:

  1. Does this issue manifest with any other random NEW devices patched in (e.g. a laptop) that has not been previously used at the facility?
  2. Is the old model of NVR that works fine a device that previously functioned in the school?
  3. Does the issue occur only under specific circumstances -- e.g. when someone attempts to log in or stream video?
  4. Is there an IP address conflict?
  5. Is the school using port based authentication - RADIUS / 802.1x?
  6. How long does it take to lose connectivity?
  7. Do you have the model# of the NVR?

Thank you so much for your reply.

  1. Does this issue manifest with any other random NEW devices patched in (e.g. a laptop) that has not been previously used at the facility?

A - No. This nvr is the only thing that has done this.

  1. Is the old model of NVR that works fine a device that previously functioned in the school?

A - Yes it worked here before. When testing both New and Old NVR get the same IP

  1. Does the issue occur only under specific circumstances -- e.g. when someone attempts to log in or stream video?

A - As soon as the NVR comes on... takes about 30 seconds.. then starts dropping every few seconds

  1. Is there an IP address conflict?

A - No there is no ip conflict. We are sure of that.

  1. Is the school using port based authentication - RADIUS / 802.1x?

A - I dont know.

  1. How long does it take to lose connectivity?

A - Not long at all... maybe 30 seconds.1

  1. Do you have the model# of the NVR?

A - Dahua 7432

Thanks again

I'm sorry I missed a question.

NO it does not take anyone trying to connect or anything...

Shortly after the NVR comes on it starts dropping....

We can ping the nvr and see it dropping

And in the "load" section of the NVR we can see the little graph drop down to 0 every second or so

Kenny, what network subnet is the nvr (viewing side) on, and what subnet are the cameras on?

Does the network drop happen even with no cameras connected?

Are you saying once it drops that it comes back and then goes on and off every couple seconds?

If you haven't done this, goto the Main Menu under Advanced there is an icon for Abnormality.

Enable Network Disconnection logging as well as IP conflict and MAC conflict logging.

Click show message as well as email for a record.

Lets see what it says...

Not to be that guy who brings up firmware, but...

One possibility is that this is a firmware issue. Have you seen if there is a newer firmware version (or even older one) to try?

Check to see in the users log if it shows IP CONFLICT when dropping off.

I had them look in the log... it shows only 2 ip conflicts total...

The thing is... it blinks off (all cameras) about every 15 seconds.

It like a reall pattern... every 15 seconds or so it blinks off and comes back on.

Kenny did you enable all the different event logging? On my NVR they were unchecked....

Yes, it is showing all types of events in the log... has blinked off 100s of times today but only shows 2 ip conflict messages.

When we connect an older nvr.... it runs fine with up to 12 cameras on it.

When we connect this newer nvr it blinks on and off with even 1 camera connected.
We have tried several different of the "newer" units.
they all do the exact same thing on the schools network

Of course they work fine if we move them to our own LAN but we cant do that for a lot of reasons...

So with no cameras it doesn't drop? What are the different subnets of the cameras and the outside LAN?

What's the model of the old NVR?

Not sure... its a 16 channel thats over a year old for sure.

I am checking on the subnets and if it drops with no cams connected

The ip is like

The subnet mask is

The gateway is

So both the cameras and the LAN where the viewing clients are on the same network subnet?

where the DHCP being served?

Kenny, here are my settings after restoring network defaults on my Dahua 4 port clone: so the NVR on the LAN is, and the on the camera side it's DHCP is not enabled on the LAN side. Do you have similar screens?

Is there any chance that the one of the NVR POE ports is connected to external LAN?

Yes they are on the same.


Cams = etc

No, they are no using DHCP.
All addresses are set statically.

If you only have one network, I think that's a problem, though on mine it doesn't let me make them the same.

what is plugged into the LAN port on the NVR?

My NVR actually has two IP's one on each network. Do you have screens that look like mine? Can you post them?

Does the client have their own LAN?

The only thing we have NIC 1 in the back of the NVR connected.

The cameras and the NVR are on the same subnet.

This works fine when connected to our own LAN that we can create with just a router and a switch.

but when we connect it all to the schools network the nvr drops connection every 15 seconds or so consistently.

We have tried several of these 7432 model dahua and they all do the same thing.

I am remote so cant really get those screens right now...

But we have set this up this same way for a couple of years... many many times.

The nvr and the cams can be on the same network with no problem.

This is what the back of the 7416 should look like. Is yours 7432 the same with more POE ports?

Correction, I see that 7432 has only 16 POE ports on the back, so it should look just like the diagram.

So, to be clear, your not using any of them?

No, we are not using any built in POE.

We are only using NIC 1

Ok, I don't know about the old NVR, but the way these new Dahua NVR's work is that they have two seperate network interfaces which the NVR straddles.

Normally you connect the cameras to the POE switch (whether they are using POE or not), either by plugging them all in there or by connecting your own external switch to one of those POE ports.

This gets them on their own 10.x.x.x.x network. Then you connect the NIC1 port to the client LAN.

You may be able to make these NVR's work with everything off of NIC1, I'm not sure (paging Jon Dillabaugh). I'll see if I can make mine do it.

Do you need to have everything on the same network? Like because you need individual camera acccess from everywhere?

If not I would recommend setting it with two seperate networks.

We have only ever used the non-PoE NVRs from Dahua, so I don't have experience to draw upon here, but my gut says to add an additional L2 switch between the NVR and the switch it is currently plugged into. Just a hunch. It may be that the NIC in the NVR and the switch don't work well together.

Turns out that it was a non-POE NVR, read below...

How did you get to those screenshots you took?

I dont see anything like the last screenshot you posted.

With 'switch" settings on it and the 10. address listed.

On the first screen there (on mine) is a Network Settings button to hit to get to the sub screen...

I could be talking out of my a** to imply that all the new Dahua NVR's have two network interfaces, so I'm trying to verify that.

I am looking for your documentation specifically. The old NVR looked physically the same on the back, with a built in switch?

There are no POE ports on the back of this 32 channel NVR.

Its brand new. Just came in this week.

No these have just 2 NIC ports.

I am almost sure that its some switch port setting in the schools network etc

Sorry to take you on that POE tangent...

Have you looked in the Remote Device Info screen, its under Main Menu, then Info.

It has a connection log, there might be something in there corresponding to the dropouts...

(assuming you have a Remote Device Info screen...)

The 7432 doesn't have a built in switch, the 7432P does.

You can put both LAN ports on the same subnet. It's not like the built in switch models where the PoE ports must be on one network and the LAN port on another.

Thanks Ethan.

Check the port settings on the uplink to the school switch and the NVR. I have seen NVRs that don't auto detect properly, and when you force them to 100/full or gig, they work better. Make sure to check both sides.

Aaron - That was my first thought! BUT...

The dahua NVR does not give you any way to check that setting.

I called support and they told me it was set to auto-negotiate by default.

Yeah. Annoying that many don't give you the option... Anyway, check the setting on the switch, and make sure it is set to auto, or maybe try to force it on the switch....

This works fine when connected to our own LAN that we can create with just a router and a switch.

Can you use that switch (mentioned above) that definitely works with the Dahua NVR, and then connect that switch to the schools switch?


Try to force to which setting on the switch?

If its not on auto we will try that first....

after that i can only guess...

Try to force it to 100Mbps/Full duplex.

Then try forcing it to 1Gb.

Hi Kenny, does the new NVR connect to the school's switch via the same cable and port on the switch as the old NVR used to do? If not, please try that and see what happens.

Is the new NVR plugged into a power board with other equipment? If so, try to isolate the NVR from any electrical interference. For example, make sure there's not a fridge or an oscillating fan connected to the same powerboard!

Does the school have switches connected to one or more levels of sub-switches? If so, try connecting directly to the top level switch and see what happens.

Do all cameras only go blank when monitoring remotely or also on a monitor directly attached to the new NVR?

Is the recorded video interrupted or is it all intact?

Sounds like you have a switching loop / broadcast storms problem in your network. Make sure you do NOT have multiple connections (more than one patch cord connected) between switches, with the intention of having connection redundancy.

How to prevent LOOPS using Spanning Tree Protocol (STP).

I concur checking switch settings makes sense. This sort of sounds like a link renegotiation loop. If you have managed switches of some form you can check their status. I also agree this could be some sort of spanning tree loop. Check the ip's , check link speed matches, check switch for status of that port, try another switchport (I think most of those were mentioned already.)

Did this ever get resolved?