Hey @Hans_Van_den_Bent so sorry that it took us so long to respond! I see that you have received some great information from others in this post already, but I wanted to let you know that the Core device you are using is not supported by Roon - you can read more about this here: Rhein Z1 Roon Server : official or unlicensed? [—> unlicensed]
For this reason, we recommend that you use a different Core device, such as a Windows PC for best performance and to see if the issues persist. We’re hoping that you’re able to give this a try. If you don’t wish to use the Windows PC, you can use another Core device and compare it to the Roon Requirements to make sure it is supported: Roon System Requirements Thanks!