Hacker News Reader

That doesnt help with CGNAT.

UPnP is just automating the process of forwarding ports, CGNAT will still screw you sideways because you're behind a router you can't access or order around.

UPnP is useless with CGNAT (Carrier Grade NAT), which is what the op is talking about.

There are other ways to get seeding working, though, including IPV6, which is gaining adoption, so I don't agree with the OP.