From: https://www.cctvcameraworld.com/port-forwarding-for-dvr-and-nvr/#:~:text=Port%20forwarding%20is%20es....
What you need to do on your router?
For our video recorders, at a minimum you must enable port forwarding rules for ports 80 and 37777 for remote viewing to work smoothly. You must make 2 individual rules in your router’s firewall settings. One port rule for port 80, and one rule for port 37777.
If your Internet Service Provider (ISP) blocks any of these ports, you can always change them from the default values by accessing the network setting menu in your NVR or DVR. If you have a residential internet service plan, chances are port 80 is being blocked by your ISP. In such an event, you will make a rule for port 8080 or something similar instead of port 80. Be sure to change the HTTP port value from 80 to 8080 in the DVR's networking section. As long as you configure everything correctly in both the DVR and your router, everything should work fine.
