Debugging an App, that needs a URL to a server

I have a Xamarin Solution with an Android, iOS, and Windows mobile solution. I also have a Web Server that sits on localhost:XXXX. I need to be able to access the URI endpoints on my local, while debugging on Mobile.

While the Web Server is running I go to fiddler, and compose http://localhost:XXXX/api/Locationsand everything is correct, I get the JSON data and life is good.

However when debugging the App on any phone, I suspect the endpoint on the phone is trying to access it's own "localhost". Is there a hosts file that I can edit on the emulators? or another solution?