We don’t normally troubleshoot VMs as they sometimes have their own settings which may cause issues with Roon, but what I would suggest for you is to look over the following thread to see if this helps:
@Mykhaylo_Plyasun you aren’t going to want to hear this, but ultimately I gave up with running RoonServer on FreeNAS. Picked up a cheap NUC and it has been plain sailing. I did get it working reasonably reliably, but plugins would always reset, and there may have been other issues periodically.