Hi friend, I found some information that I hope can help you.
ONT WebUI
You can log in to the Web interface to configure your optical modem.
1. Use a provided Ethernet cable to connect a LAN port of the ONT to the PC.
2. Obtain an IP address automatically using the PC and make sure that the IP address of the PC is in the same subnet as the management IP address of the ONT.
3.Log into the Web configuration interface
Enter http://192.168.100.1 in the address bar of IE, and then press Enter to display the login interface
In the login interface, enter the user name and password. After the password authentication is passed, the Web configuration interface is displayed.
On the ONT WebUI, In the navigation tree on the left, choose WAN > WAN Configuration, and set WAN interface parameters.

NMS
You can configure the WAN port on the NMS and TR609.
On the NMS (Please use the U2000 V200R014C60 or later for configuration.)
1. Choose Configuring
2. Choose Access Profile Management
3. Choose Configure general ONT VAS profile
2. Choose WLAN Configuration in the LAN Interface Management option
3. Choose WAN Interface Management
TR069
On the TR609 (When configuring services on the TMS1000, do not modify the WAN between the TMS1000 and the ONT. Otherwise, the connection between the TMS1000 and the ONT will be interrupted.)
In the navigation tree, choose InternetGatewayDevice > WANDevice > (Instance x, x indicates the instance sequence number) > WANConnectionDevice
For more information on ONT, please click: How to login Huawei ONT, and FAQs
Thank you~