ejabberd/EXTRAS/example-configurations/conf.d/41-s2s.yml

listen:
  -
    port: 5269
    ip: "::"
    module: ejabberd_s2s_in
    starttls_required: true
    max_stanza_size: 524288
  -
    port: 5270
    ip: "::"
    module: ejabberd_s2s_in
    tls: true
    max_stanza_size: 524288