@Art_Lustgarten, welcome to the community and sorry to hear about your issues getting ARC configured. Can you copy the error message shown in your Roon Settings → Roon ARC tab? This message can help the community and Roon staff to diagnose what you are experiencing.
I also moved your post to the Port Forwarding support category which may be seen by others.
Also … this message is generated AFTER the ‘My Spectrum’ app allowed me to (1) reserve the IP address for my Core; (2) open a port designated both internal and external port 55000 and (3) protocol changed to TCP
Thank you @Art_Lustgarten. The diagnostics you’ve provided suggest that your Core is having difficulty reaching Roon’s servers. There are several independent factors that can cause this error, so Roon recommends double-checking the following to initiate troubleshooting:
Is your router firmware up to date?
Do you have any VPNs, proxy servers, or enterprise-grade security on this network?
Are you experiencing any issues with Roon Remotes, or other apps on your local network?
If you continue to experience difficulties, please tag the support team and include the following information:
What is the make and model of your modem and router?
Do you have any additional network hardware, like additional routers or managed switches?
Who is your internet service provider and what is your geographic region?
Is your Modem configured in Bridge Mode so that it operates only as a modem or do you have the ports forwarded on both?