Hi @officiallep,
This error indicates that while UPnP is available in the router, it’s not configured to automatically set up port forwarding.
The first step here is to access your router’s web administration page.
I’d first verify that you haven’t inadvertently exposed the network by placing anything in the DMZ (in front of the firewall) or manually opening every port.
Next, since UPnP isn’t configured, find a section labelled “Port Forwarding” or similar. It’s sometimes in the firewall and security settings.
Create a TCP port forwarding rule using the IP Address and Port listed in Roon Settings → ARC.
If you’re still receiving a “Not Ready” error, then you’re probably behind a layer of CG-NAT (address translation) on the part of your provider, SC Broadband. You can reach out to them to ask if a dedicated WANIP address is available for port forwarding.
Alternatively, you can install Tailscale both on a machine in your network and on your phone to create a virtual subnet. There are instructions over in Tinkering here: Tailscale implementation on ROCK (NUC) To circumnavigate ISP CGNAT for ARC.