New
#780
Thanks for getting back to me so quickly. I don't know if it answers your question but the notebooks were bought including licenses. However, the idea was to take the notebooks out of the box and install our custom image instead of booting into the manufacturer's image first in order to save time. So i would have to test if it activates properly when booting the manufacturers image (HP in this case).
When i run slmgr in command line it tells me the license type is "OEM_DM channel". Windows version is stated as "Windows, Professional edition". In my answer file I specified the generic key for Windows 10 Pro listed in this guide. If i'm not mistaken, reinstalling a device with an OEM license should be possible as long as the hardware doesn't change.
What i don't understand is why the activation works flawlessly when the device has a wired connection to the internet during installation. If it doesn't and i connect to a wireless network after the setup is complete, activation fails with the afore-mentioned error text. I then have to run the troubleshooter in order for it to activate, which is an extra step i would like to eliminate.