Why am I sometimes unable to access the internet through my app even when my device is connected to the internet?

[Windows Central Question]

Sometimes I am unable to access internet through my app even my device is connected to internet

I created an application using WinRT and C# I am trying to hit a service in azure through my app, but sometimes it is unable to hit the server even my device has internet, firewall etc everything is checked, Can any one help me plz...