Weird problem- Internet works only when i switches on a vpn

I am facing a very weird problem for last 3-4 days, I was not able to access any of the site on any browser(tried 4 different browsers) but blue stack and steam were working fine. So today i installed hotspot shield and after switching it on everything is working fine -_-
Still i cant use internet on my phone through wifi maybe becuase i havent installed any vpn on phone yet.

What is causing this issue? Please help asap as MTNL, Delhi people wont help me i am aware of that.

PS: I am using modem + router- TP link- W8961 ND