Hi,

I live in Qatar, and here ISP provide Fiber to home service. I plan to buy HAP AC and GPON ONU module. my question is: how can I know if GPON ONU module is compatible with my ISP FTTH service or not, and what is the required configuration I need to connect my HAP AC to my internet service through GPON ONU module

Try to ask your ISP for help. They should have some compatibility tables for used devices.