Hello Rajdeepsaha1456,

Before stopping the Fiddler Everywhere application, you could make sure that the Capturing switch is turned OFF. This way, the system proxy will be reset to its default, and when Fiddler Everywhere is turned off (or wholly uninstalled), there will be no leaked proxy.

However, if the Internet connection is missing after stopping Fiddler, the first thing you could do is check for leaked proxy settings. On Windows 10, go to Proxy Settings and verify that the Manual |Proxy configuration is reset to your default settings.

KB article about restoring the internet settings for cases when the Fiddler proxy has leaked.

https://docs.telerik.com/fiddler-everywhere/knowledge-base/no-net-after-fiddler-exit