REST api call : Failed to connect to localhost port-Connection refused

I am working on Hololens app development. I am facing an issue when i make a REST call using UnityWebRequest or WWW in HoloLens Emulator built with Release mode-x86-HoloLens Emulator.

Following is error message -> Failed to connect to localhost port : Connection refused.

I have enabled InternetClient ,InternetClientServer Capabilities in Unity.

Same issue is not observed when i make a REST api call in Debug Mode with settings as x86 & Local Machine.

I am able to browse the REST api call in Hololens Emulator Edge browser and see the data.

Please help me.