Cannot enter the WebGUI under VPN connection

[gizmo]

Hi there,
When I'm connected to my office via VPN connection for some reason when I try enter the WebGUI via my local Firefox and IE8 I get the error of Error code: ssl_error_rx_record_too_long (https://fw/). When I connect to one of my servers via RDP and open the local browser on the server everything is going fine.

Any idea you guys?