Allow changing the ONU serial (for ISP compatibility).
: If you have a legitimate firmware file (often with a .uImage or .bin extension), you can upload it through the "Local Upgrade" section. Caution: Always use firmware specifically designed for your exact model to avoid "bricking" (permanently damaging) the device. Firmware Gm220-s Firmware Gm220-s
To develop a feature for the (a GPON ONT/ONU, often used by ISPs like China Mobile), you need to work within its OpenWrt‑based firmware environment. Below is a structured approach, from understanding the device to implementing a new feature. Allow changing the ONU serial (for ISP compatibility)