Yes, using the same web upgrade method, but you may lose full functionality.
This write-up explores the functionality of the GM219S, the significance of XPON firmware, and the technical implications of flashing a "Full" firmware version. firmware gm219s xpon full
After flashing the full firmware, the device is now universal. Here’s how to configure it for your ISP: Yes, using the same web upgrade method, but
– A video demonstration of the latest "green" firmware interface which supports PPPoE and Hotspot configurations. Google Docs Key Device Specifications using the same web upgrade method
If web upgrade fails or you need to flash a bootloader, use TFTP: