The recent downloading speed is around 6 Mbps during the day as the traffic is very high. During the night the speed definitely increases but the increase is not that significant since people are awake at night too. When you are allotted your hostel rooms you will get an Ethernet cable. The speed might improve if you use the Ethernet instead of the wifi. In recent years a network with 1 Gbps bandwidth has been set up which resulted in good internet speed.

This might look very high speed to some people reading this answer, but actually this is a pretty normal speed considering its an IIT. IIT Roorkee has far better speed than this.