Hi Tristan, did you solved it somehow? There are more people with the same issue (small discussion with Ian Hutton under the Second Revised method for deploying StageNow profiles to a remote FTP server)
I indeed solved it by adding the public ip as a secondary Ip address on the network interface. We basically use StageNow as a real FTP server and not a local one.
However if you all the devices are intended to be on the enterprise network then you could just keep the lan ip on the StageNow machine and make it accessible accross all Wi-Fi networks on your enterprise premises all around the world.
That way, devices can connect to the machine hosting the StageNow application and download any files you want, remotely, simply from scanning a barcode. And it keeps you from changing the XML's and whatnot with FTP info etc.
This feature should definitely be added, this is a very modern way of managing devices and it eases deployment accros multiple locations by a VERY large amount