> > or you can manually create a new netns with "podman network create <name>" and then join all the containers to it with "--network=<name>".

> I don’t think this has the desired effect at all.

Well I'm not entirely sure what effect you're wanting here, but I use this option for some of the containers that I run, and it makes it so that all containers in that network can reach each other, while anything outside that network can't. You can also use "--network=ns:/run/user/$UID/netns/<file-name>" to join a container to a manually created network namespace (created with "ip netns add <file-name>") if you need more control.