You can change the Windows proxy server settings on each computer in your office to route your network traffic through the proxy server.

Just set it to enabled, refresh the policy on a machine (or reboot) and set the proxy settings in IE.

Internet Explorer shares proxy settings with Windows. Therefore, disabling the proxy server in Internet Explorer also disables it for other Windows applications.

Go to Computer Configuration, Administrative Templates, Windows Components, Internet Explorer. There is a setting that says "Make proxy settings per machine (rather than per user)." Enable that ...