Which Ports does Oban Need?

Hello, everyone!
I have a Phoenix 1.7 app with Oban as a dependency running in a Fargate container behind an application load balancer on AWS.
I tried allowing only incoming TCP from the ALB and the DB into the app container, but I get this in the logs:

** (EXIT) time out
(stdlib 5.2) gen.erl:276: :gen.do_call/4
(stdlib 5.2) gen_statem.erl:923: :gen_statem.call/3

(postgrex 0.17.4) lib/postgrex/simple_connection.ex:217: Postgrex.SimpleConnection.call/3
(oban 2.17.3) lib/oban/peers/postgres.ex:82: Oban.Peers.Postgres.handle_continue/2

(stdlib 5.2) gen_server.erl:1085: :gen_server.try_handle_continue/3
(stdlib 5.2) gen_server.erl:995: :gen_server.loop/7
(stdlib 5.2) proc_lib.erl:241: :proc_lib.init_p_do_apply/3
Last message: {:continue, :start}

[error] GenServer {Oban.Registry, {Oban, Oban.Midwife}} terminating
** (stop) exited in: :gen_statem.call(#PID<0.3572.0>, {{:listen, #PID<0.3575.0>, [:signal]}, #PID<0.3575.0>}, 5000)
** (EXIT) time out

When I open up the Fargate container to all TCP from any IP, things seem to work.
I’m confused by this because I assumed Oban only needed the Postgres port (5432 default), but I haven’t been able to find any documentation on it. What am I missing?

Thanks in advance for your help!