Hi @Stephan_Groth,
Thanks for those additional details.
We have been testing Windows Server 2019 in the QA lab and we have found that we could not get it working using a standard install procedure and as such, we have removed support for this platform and updated our Minimum Requirements Doc
It might be possible to get Windows Server 2019 working with Roon by using further tweaks, but as to what those tweaks are, I cannot say.