Windows Store blocked by server

I am setting up an Acer Iconia that has Windows 8 installed and after setting up the server connection I can't access Windows Store. The message i get is: "Your network proxy doesn't work with Windows Store." I have changed firewall settings to allow the tablet through the firewall but still get that message. What is the ip address for Windows Store so I can allow "no user authentication" for it?

I am setting up an Acer Iconia that has Windows 8 installed and after setting up the server connection I can't access Windows Store.

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Do you mean you are in a domain?

IT Administrators can control the availability and functionality of Windows Store to client computers based on the business policies of their enterprise environment.

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Managing Client Access to the Windows Store

We have a linux server but can log on to it without joining a domain. The server allows internet/emil access as well as being a file server.
I am looking at the link you provided for further info.