It took 15 days to complete installation, had to visit BSNL CTO office for it. They are very busy because of fiber cuts caused by metro construction. Pings were 280ms to most international servers including Singapore, emailed Nagpur NIB and then they emailed Pune NIB and then pings were fixed in 30 minutes of email.
Ping test - 73 ms - 2018-05-24 19:26
As you can see, the speed is not actually 40mbps but IMO it is not worth arguing about with them.
Connection is very good if you like to play games as there are no ping spikes and no packet loss.
Twitch and YouTube also work in max quality.
Netflix is the only the major problem with this connection, 1080p content always plays in 4-5mbps bitrate but 7.15mbps is that max bitrate for 1080p content on Netflix, 4k content surprising plays in 15mbps which is the max bitrate for 4k but it takes upto 10 minutes to reach the max bitrate.
Currently happy browing offer is active which means no FUP.
EDIT: Netflix is more inconsistent at 4k than I thought.
EDIT 2 : Overwatch 80ms Singapore, Battlefield 4 130ms Germany.
EDIT 3 : Nagpur NIB office number 0712-2557071