I am using this internet for 3 years now. At the beginning, I faced some issues but now it never disconnects.
But the 512 plan I used, irritates a lot. So I upgraded to the 1 Mbps plan.
If you have this plan in my vicinity i.e Kandivali (E), you should have no problem of disconnection as the MTNL does.
If you have any connection problems, probably Hathaway is new to your area.
So, it will take maybe 3-4 months, until you have a stable and reliable connection, . But don’t opt for slow speed plans and blame Hathway for that.