Hello friend!
Via DDNS, which associates a static domain name to the dynamic IP address of its host, users on the Internet can access the server only with domain names.
1. In most cases, the default user name for logging in to the web page is root, the password is admin and the IP address is 192.168.100.1. However, for security reasons, the default password or IP address may have been changed before delivery. The nameplate prevails. Enter the IP address in the address bar of your browser.
2. Enter the default login account and password on the nameplate on the rear of the ONT and click Login.
3. Click the Network Application tab and then choose DDNS Configuration from the navigation tree. In the right pane, configure the DDNS parameters, including Service Provider, Host Name, Service Port, Domain Name, Username and Password.

4. Click Apply.
The Dynamic Domain Name Service (DDNS) associates a static domain name to the dynamic IP address of its host.
Thanks!