Hi m.matejkowski,
Queueing can be done for a persistent session client subscribed to a topic. Here are a few sections of the HiveMQ documentation on these topics if you haven’t checked already:
https://www.hivemq.com/docs/hivemq/4.10/user-guide/configuration.html#mqtt-config
https://www.hivemq.com/docs/hivemq/4.10/user-guide/configuration.html#session-expiry
https://www.hivemq.com/docs/hivemq/4.10/user-guide/configuration.html#msg-queue-size
My colleague Dasha also gave a good outline for testing these concepts using our MQTT-CLI tool in another thread that may be useful for you:
https://community.hivemq.com/t/persistant-session-queuing-message-session-expiry/1578/9
If these don’t get you started, please let us know here how you are setting up your tests with MQTT.fx. It may also help if you post your config.xml.
Thanks for your interest in MQTT and HiveMQ!
Seth - HiveMQ Support