Untangle is probably acting as a proxy server, though I'm not going to study the documentation to make sure. It's probably also acting as a router.
You need to make sure that ports are forwarded from your router to (probably) your Untangle server, and from your Untangle server to your Windows Home Server 2011 server. Specifics for configuring Untangle are obviously beyond the scope of these forums,
so please consult a forum specifically for that software for more help.
I'm not on the WHS team, I just post a lot. :)