Connection timeout from work, working anywhere else

[GuiPoM]

Short update, as I am still struggling with this problem: Same issue for
HTTP, if I route an external port to nginx on my raspberry. But if I route
to another HTTP server, everything works fine from my work office. So this
must have something to do with nginx, but I have absolutely no idea where to
have a look and what to do. Any help would be very appreciated !

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,258187,258289#msg-258289