If you're using the DEB or RPM packages you can change Zammads environment variables by the following commands.
zammad config:set ZAMMAD_BIND_IP=0.0.0.0 systemctl restart zammad
Please note that you also have to reconfigure Nginx when changing the ports!
zammad config:set ZAMMAD_RAILS_PORT=3000 zammad config:set ZAMMAD_WEBSOCKET_PORT=6042 systemctl restart zammad
Per default one application server will get started. If you have more http requests (user sessions) you need to increase the amount of your application server. The typical problem is long waiting times in the web interface for opening or editing tickets.
zammad config:set WEB_CONCURRENCY=3 systemctl restart zammad