Airtel — airtel network issues. 4g not connecting. exclamation mark

Address:

Hyderabad, Telangana, 500083

4g data connection, mobile data shows 4g but, a small exclamation (!) mark appears in the network icon and internet does not work.
Even if i set preferred connection as 3g network, after a while 4g gets connected automatically.

Other airtel users in my area have no problem with the data connectivity.
I tried using other sim cards (Airtel 4g) in my mobile it works fine,
I tried getting new sim card still no change.