@Clive_A I have attached my main ISP router configuration screen shot further my ISP doesn't have any problem for replacing the main router with ER707-M2 So kindly advise me which SFP module is...

Hi I am going to buy ER707-M2 and i want to remove my old Huawei HG8546M (GPON ONU) With ER707-M2 by using SFP port please let me know how is it possible and which SFP module I have to by for it