We've got an IoT Core device with a small display running three processes. The device is located behind a firewall and only have limited access to the internet. The two background processes are running fine straight from start up but the foreground process hangs, displaying the splash screen with a cross symbol. If we open the firewall the process starts up as it's supposed to. The "hang" happens before the user code is entered, we seams to be in some kind of bootstrap part of the application. When we look at the IP-addresses that the device it trying to access they are all Microsoft addresses and most of them are related to windows update.
What is the nature of this hang? Is it a license check? How can we prevent the foreground process from hanging without opening up the firewall? We tried opening for all windows update dns entries that Windows 10 uses but this specific firewall does not permit wildcard dns in its rules.
The app is plain UWP.
If you have a store-signed app you will have to install the license file. The easiest way to do that is to specify the license file in a provisioning package. See the second half of this page: https://learn.microsoft.com/en-us/windows/iot-core/develop-your-app/appinstaller
If the license is not installed and your device can reach the Windows Store servers it will retrieve the license that matches your package from the server. This is likely the activity that you were seeing.