Bandit servers are just Thousand Island servers under the hood, and the latter provides a first class way to shut an instance down via the ThousandIsland.stop/2 function. See the docs for details.

As to the ‘process attempted to call itself’ error, the connection_pids/1 and listener_info/1 functions both expect to be handed the PID of a running Thousand Island server (ie: you would use them like so:

{:ok, server_pid} = ThousandIsland.start_link(opts)

# You can store `server_pid` away as you'd like, and call this at any time that the server is still running....
ThousandIsland.listener_info(server_pid) |> IO.inspect()