- For a system wide proxy you need first manually set IE proxy.
- You can also use 'PAC' proxy settings instead.

- Because they are forbidden to send network traffic to the local computer in case of improper connection.
- This defies the use of loopback method, hence the proxy.

- You can use the command-line tool called 'checknetisolation' to add certain app to the exempt list.
- The exempted metro app uses IE proxy to connect by default.
- There are third-party tools to do this job at ease.
- The tool 'fiddler' for example is recommened for this purpose.

- Install and open it
- click 'win8 config'
- check the box behind which is the app you want to exempt.
- save config.
- If you want to set another proxy than IE, you can also fill the proxy address in the same page.

netsh winhttp set proxy "proxy.sysadmit.com:8011" "; 172.17. *"

HKEY_LOCAL_MACHINE  SOFTWARE  Microsoft  Windows  CurrentVersion  Internet Settings  Connections

Key Name: WinHttpSettings