Hey @Thomas_Smith — Thanks for reaching out!
I’d be happy to take a look at what you’re experiencing here and get this working for you. 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.
When you open the Web Display URL in your browser, you should see the browser appear as a Display under Settings > Display, and also from the Display menu from the volume button, so something is preventing Roon from being able to recognize the web Display. Do you have any active antivirus or firewall on the Core machine? If so, try disabling them temporarily and let me know if there is any change!
Since installing have you tried rebooting the Core machine?
Thanks!