If the ONT no longer responds to 192.168.1.1 :
Official firmware for ZTE devices is typically distributed through service providers or the official manufacturer portal. ZTE ZXHN F660 V7.1 Download Firmware - AliExpress
: Adds cosmetic UI changes, IPv6 dual-stack support , and a traffic prioritization engine designed for intelligent home networking.
Assumptions: You have a valid firmware.bin file, your PC is connected via Ethernet, and you have the admin password.
Do download firmware from: