If you manually alter the firewall discovery then you might generate Phishy requests as well as requests that are not in your application and will generate a 404 request by the web server
Requirements
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2