We have added to Splynx a module to manage Huawei GPON from splynx.
For using Huawei GPON you should install it like addon:
apt install splynx-huawei-olt
To add an OLT, go to Networking → Huawei GPON, it needs IP, ssh port, and login/pass. Also it's so important to set correctly the UPLINK BOARD and the UPLINK INTERFACE.