I’m sorry to hear you’re among the customers for whom carrier-grade network address translation is blocking ARC in its current implementation.
Please note the team is working diligently to build mechanisms to enable automatic port forwarding with the most common implementations of CG-NAT. We hope to include this updated compatibility in a future release. You can see a list of known ISPs with CG-NAT and updates on our efforts here: https://community.roonlabs.com/t/isps-and-routers-list-of-known-solutions-and-workarounds/203656