If you are using IIS Express you may need to bind to all hostnames instead of just `localhost'. Check this fine answer:
https://stackoverflow.com/a/15809698/383761
Tell IIS Express itself to bind to all ip addresses and hostnames. In your .config file (typically %userprofile%\My Documents\IISExpress\config\applicationhost.config, or $(solutionDir).vs\config\applicationhost.config for Visual Studio 2015), find your site's binding element, and add
<binding protocol="http" bindingInformation="*:8080:*" />
Make sure to add it as a second binding instead of modifying the existing one or VS will just re-add a new site appended with a (1)
Also, you may need to run VS as an administrator.