I am behind a corporate proxy server which requires credentials. I have been trying to connect to a TFS server (on tfspreview.com) with MS Visual Studio Pro 2012
I was trying to connect Visual Studio 2013 to Visual Studio Team Services, and am behind a corporate proxy. I made VS use the default proxy settings (as specified in IE's connection settings) by adding:
<system.net>
<defaultProxy useDefaultCredentials="true" enabled="true">
<proxy usesystemdefault="True" />
</defaultProxy>
<settings>
<ipv6 enabled="true"/>
</settings>
</system.net>
to ..\Program Files\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe.config (running notepad as admin and opening the file from within there)