I use this addr format in connect:
ipfs swarm connect /ip4/104.131.131.82/tcp/4001/p2p/QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ
You need to get and broadcast “relay” version of your address otherwise others cant reach your node behind NAT. I have same experience as person in following post. Sometimes your node broadcasts its relay address version but most times it does not. What might help is to enable “EnableRelayHop” on your other node with public ip and swarm connect to it.
Other possibility is to try setup ipv6 tunel from https://www.tunnelbroker.net/ it works behind some but not all NAT boxes. What might help in future is TOR transport because tor nodes behind NAT can reach each other. In current state you need to setup some kind of port forwarding (upnp, ssh, tor, vpn, router port forward) to become “full” node.
i dont think autorelay feature is very reliable. Its just for emergency use if you are only node hosting something and other persons are willing to wait a lot to get your content it might work after long time (even hours). Then your content will replicated and become more easily accesible. Its same for bit torrent if there are no seeders without NAT then its very difficult to get missing parts. Bit torrent has advantage of retrying downloads even for weeks as long torrent is in download queue while ipfs gets tired of retrying.