If you are using a numeric IP address instead of a computer name to identify your Web server when creating an application, you may encounter an authentication error. This happens when your computer uses a proxy server only for external addresses. You can avoid this error in one of three ways.
Your first option is to use the computer name instead of the IP address. Your second option is that you can include the computer’s IP address in the lists of hosts without proxy within your Web project’s proxy options. Your third option is to change the operating system’s Internet properties by adding the Web server’s IP address to the List of hosts without proxy.