Suddenly, I can't view the live view of the cameras on Zmodo ZP-NC18-S on Internet Explorer but I can ping the IP address of the NVR, although I can view the cameras using the monitor plugin direct to the NVR.

This was caused by the latest firmware version 43.0.2.0 which got updated automatically somehow.

To fix it, I had to reapply the older firmware, version 43.0.1.7 firmware was the one I used.

But how did I reapply the firmware, one way is to plugin a USB stick direct to your NVR, but I'm physically located where the NVR was so I had to do it remotely.

I installed a ZViewer v2.0.1.6 or 1.0.135 then add the NVR's IP, enter the username admin, but leave the password blank. If you enter the default password 111111, you will get an error "Please enter the correct login password"

You can then go to Settings and you will be able to go to Software Update and downgrade the firmware. Firmware can be downloaded from here. This will downgrade from version 43.0.2.10 to 43.0.1.7

Your NVR will reboot and after that you will be able to view the NVR again via Internet Explorer.

Don't forget to reset the admin password from blank to something else and re-add the users as it disappeared after it got updated to 43.0.2.0.