Since software version 3.2 you can perform updates via Web-GUI. If you would like to perform a software update on your device, please go to menu Settings > Updates > click the button "Check for software update now". The device will connect to update server and download the update package automatically.
If your device is working in an offline environment, please please submit a support request In the request, please give a MAC address of your device and the current software version on your device.
You can track a history of software changes on Software updates page.