I would also double check to see if you are being connected via CGNAT. Many posts online seem to indicate you ISP has switched to such. This would involve a call to your ISP and asking, and if you are on CGNAT, you can ask that they take you off and give you a public IP address for port forwarding.
Thank you for your patience while we’ve diligently worked to reach every request for support with port forwarding. The diagnostics you’ve provided suggest that UPnP is not properly configured on your router.
Please first try the following steps:
Try to enable UPnP/NATPMP in the web administration interface for the router directly upstream from your Core
Try to manually open the port in your router’s port forwarding configuration
Make sure the IP/Port matches the Port listed in Roon → Settings → ARC
Check for any VPNs or Firewalls that might be interfering
Check if your modem is in Bridge mode or forward the port on both modem and router