: You need a specific firmware file that includes the EPON configuration. This is often a modified version of the original Huawei firmware.
Huawei explicitly states that their ONTs (Optical Network Terminals) do not support conversion between GPON and EPON. firmware huawei hg8245h gpon to epon
This process is unsupported by Huawei. You can permanently brick your ONT. Do this only if you have a serial console (TTL) recovery method ready. : You need a specific firmware file that
GPON relies on ATM-based GEM (GPON Encapsulation Method) framing, while EPON relies on standard Ethernet framing. firmware huawei hg8245h gpon to epon