async_client does not use MQTTAsync_connect5 when connecting to MQTT brokers with protocol version 5 about paho.mqtt.cpp HOT 2 CLOSED

I just figured out that I also have to create the async_client instance with create_options specifying MQTTVERISON_5 for this to work. Closing this.

from paho.mqtt.cpp.

Yes. That requirement will go away in the next version, but for now you need to specify v5 when creating the client.

Also, though, you are calling clean_session() which might cause a problem. That is a v3 option. For v5, use clean_start(). Although it applies to the same bit in the connect packet, the underlying C library makes a distinction between the two, requiring us to use clean_start for v5.

But that is good, since using clean_start should remind you that with v5 you need to specify a session expiry interval as a property with the connect options. Otherwise the expiry interval is assumed to be zero (0) seconds, and the server will end the session as soon as the client disconnects.

See the various "_v5" examples for how to set the session expiry interval.

from paho.mqtt.cpp.