I’ve moved your post to the Support category of the forum, where it will be seen, and responded to, by a member of the Support team.
Can you describe in detail what you see when you say you “can no longer open the app”? It doesn’t open, or you get a blank window with the Roon logo, or there is an error message?
In order for Roon’s @support team to better assist you, please provide a brief description of your current setup and the nature of the issue using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so they have a clear understanding of how your devices are connected.