Hi @Markku_Huusko,
So we can better assist you, please provide a brief description of your current setup using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so we can have a clear understanding of how your devices are communicating.
How many tracks total do you have that are importing into Roon?
Can you click the blue spinner and share a screenshot of the import screen?