If I create a new torrent, does CGNAT (carrier-grade network address translation) prevent me from being an initial seeder of that torrent? I’ve made test torrents before and noticed that none of them seemed to be downloadable. Seeding the test torrents on a VPS of mine with a public IP has surprisingly worked before.
I can download and upload in my torrent client just fine, so I know my ISP isn’t (intentionally) blocking and firewalling torrents.
If your box isn’t globally addressable (because of NAT), your box can’t be connected to. It works one way only, from the inside out - because the NAT-router keeps track of the connections your box makes to globally addressable hosts and forwards reply packages back to your box.
You could use IPv6 which because of the vast amounts of ipv6-addresses, eliminates the need for NAT. Or you could use a VPN or a tunneling service which gives you a dedicated IP. Or port forwarding from a globally addressable host. Either self hosted or as a service. Switch to an ISP which doesn’t do CGNAT.
In short: ipv6 is easiest.:)
Edit: does anybody know if a non addressable seed box gets info about interested and globally addressable peers somehow (either tracker or tracker-less) so it can initiate a TCP connection to those peers? Are there resources to read up in that topic?