No matter we are using IP cameras, DVRs, or NVRs, we want to remotely access them via different devices. Currently, there are two methods to achieve remote connection; P2P (also called plug&play, a network protocol can automatically punch holes on firewall of router), and DDNS.
P2P makes connection super easy, but lacking flexibility and controlling. Users can set DDNS manually for their IP cameras, DVRs, NVRs. You can do port forwarding to specific ports and create specific firewall rules to protect your cameras from possible authorized accessing. Typically it only requires three simple steps to set DDNS successfully.
Read the manual or go to device's network setting webpage to know what DDNS service providers your device can support, then register an account
Doing port forwarding for your devices in the router, the port number is the number which you locally access camera via web browser, or protocol's port number for video streams.
Input DDNS information in your device (IPC, DVR, NVR), saving the settings and reboot your device.
Although you followed instructions carefully to set DDNS, your devices still might not be accessible. To debug the problem, foremost we need to ensure the account info and port numbers are correct. "Yes, all steps are correct, account info and port numbers are correct, but I can't access it remotely." If you can locally access but fail to access it remotely. According to my existing knowledge and experience, the problem comes from two aspects; port is blocked by ISP (internet service provider), your ISP provides a private IP address.
There are many reasons why ISP decides to block certain port numbers, the most common one is 80. 80 is the default port number for web service, it could be easily attacked by DDOS or hacking. If the port number is blocked, you should change port numbers in both your devices and port forwarding rules in router.
Due to fact that public IP addresses (IPv4) are not adequate to the growing number of Internet users. Some Internet Service Providers (ISP) provide private IP address for Internet service. A private IP address is, in contrast to a public IP address, not allocated to a specific organization, but can be used by anyone without approval from a regional Internet registry. Private IP addresses can only be reached within a closed network and are not directly accessible from the outer Internet.
Using private IP address means your IP cameras/DVRs/NVRs are not accessible by Internet users. many Chinese users can not use DDNS due to this reason. China Telecom, the state-owed ISP, it provides private IP address to residential users. Residential users normally can not use DDNS service unless they make a request for switching private IP to public IP.
The private IP address range is 10.0.0.0/8, for example 10.169.215.137 and 10.169.129.147 are private IP addresses. To know whether you're using private IP or not, you should logon admin page of router, check Internet connection status, if it shows you a private IP address, it means you're using private IP address.