I have a ER605 acting as a router between my main network and my camera network. I want my cameras to be isolated from the rest of the network.

The router is set up to have the cameras and the network video recorder all on a 192.168.x.x subnet and the rest of the network is on a different 192.168.x.x network.

The port configuration is the default of 1 WAN and 4 LAN ports.

The ER605 is doing DHCP for the LAN network. It gets it WAN IP from my main network router.

I have a OpenVNP set up so I can tunnel into it and confgure it from PCs on the main network as needed.

I have the DMZ set up to point to the network video recorder. This allows computers on the main network to be able to connect to the NVR so view cameras via the NVR.

When I first set this up it was working great.

Then without any changes that I can figure out the computers on my main network that try to access the NVR are not able to do so. I do this via a web interface to the NVR and also software installed on the PCs.

When I use the web interface it will show the login page. I put in credentials and then it takes forever sometimes showing the "network page is not responding, exit or wait" that chrome shows when a web page locks up.

If I wait, then usually it will come back for a second and progress to the main page and then lock up again right away.

So it does respond, but very very slowly.

I also have a PC connected to the ERt605 via a LAN port. When I do the same web page or the same software everything works fine.

This tells me there is something going wrong with the ERt605 routing.

How can I diagnose this?