You may find you cannot connect to any website or online service with a metro app, it fails due to proxy settings. If opening up the desktop version of IE it reads the proxy settings and connects properly. However, the metro IE or other metro apps fail to connect to the internet unless unchecking the "use a proxy server for your LAN" checkbox via Desktop version IE.
A few things you can try:
Step1. Open "Local Group Policy Editor"
Step2. Navigate to "Computer Configuration - Administrative Templates - Network Isolation"
Step3. Open "Internet Proxy Servers for Metro Style Apps" and set the value to your proxy server address like 172.16.0.1:8080.
Step1. If you are logging in with a windows live ID, then go to the Desktop IE, authenticate with the proxy.
Step2. Check “remember my settings”. Then all metro apps will work fine.
Step1. Open regedit.msc
Step2. Locate to the following registry:
Step3. Set the value to zero.
Run the following command every time you boot the system:
netsh winhttp set proxy x.x.x.x:y bypasslist