Identifying NVR Internet Issues and Common Problems:

Ping the DDNS or IP address to check for connectivity. Use Command Prompt (CMD) and type "ping [DDNS or IP address]".
- If there's no result, it could be a DDNS issue, an internet issue, or a firewall blocking the connection.

Common issues and solutions:

a. Request the building superintendent to reboot the modem, router, and NVR.
b. Contact the ISP to ensure the modem is in bridge mode and that there are no service outages.
c. Check if there's a firewall blocking the connection, and adjust settings accordingly.
d. Ask the building superintendent for a public IP address to determine if the DDNS is the problem.
e. Run an Nmap scan to identify potential network issues or blocked ports. f. Verify that the router's firmware is up-to-date.

If you get a result from the ping, it may indicate a port issue or a misconfiguration on the NVR or router.

Common issues and solutions:

a. Check UPnP settings on both the NVR and the router.
b. Ensure that UPnP on the NVR side is set to manual and that the ports are correctly configured.
c. Verify that port forwarding rules on the router match the NVR's settings.
d. Confirm that the NVR's IP address falls within the router's DHCP range, or set up a static IP address for the NVR.
e. Inspect the router and NVR logs for error messages or clues about connectivity issues.
f. Check for IP address conflicts or duplicate MAC addresses within the network.