I have one more question, whenever there no power for like more than 5 to 6 hours and then when power comes again the bsnl ftth remain no internet for 4 to 5 hours or more, is this normal ? it happen to me everytime my power is out.
Not in windows. You need to login to your ONT's web UI - do you know the IP address of your ONT? Try 192.168.1.1 in web browser and login with username "admin" and password "admin" and check if you can see any WAN status page?