Move the contents of the /Cache folder elsewhere, like your desktop
Try restarting Roon and verify if the issue still occurs
You should be able to use the file manager software supplied with the NAS to access the database location. If you still need further help, please provide the model/manufacturer of your NAS.
I would also try some more basic steps before clearing the cache:
Your topic has been moved to the support section of the forum.
In order for Roon’s @support team to 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 they can have a clear understanding of how your devices are communicating.