3 things I noticed.

1. The done / busy / error outputs are not being monitored (or counted as I call it).  At first, you should count these events by adding 1 to a tag when DONE / ERROR are ON (or incrementing a tag).  In doing this, you can see how many times they happen since some of them are only for a single scan (meaning you are not likely to see them while online monitoring random scans of the logic).

2. Local Port = 0.  Give it a valid port number - at least until you get everything working - rather than having the block to auto-assign one.  You can look up online suggested ports for mqtt clients.  How about just use 1883 for both inbound and outbound MQTT traffic.  If you ever have to packet capture to analyze (using wireshark or similar tool), knowing it is MQTT traffic will help that tool display MQTT data automatically.

3. Not really a problem, but if you look at the MQTTdata.status at the output of the block, it is converted the datatype from word to whatever is defined in the DB MQTTdata for status.  The little green "triangle" means it is implicitly performing data conversion.  Should still show the status, but having the data types match helps because the PLC does not need to perform an extra task.

So, really, #1 is the only thing that's REQUIRED for you to do.  The reason I say required is because the block may well be telling you something, but you're assuming those outputs will stay on more than a single scan.

You should probably have logic in the next network that handles the done/error outputs.  If you need to know the done happened, you better set a tag so it can remember it was done, and compare it against tcpEstablished and mqttEstablished as well.

Save the status and statusID anytime the error output is ON.  A couple MOVE blocks with NO contacts at the enable inputs to the MOVE blocks should do the trick.  Something like "last_MQTT_Client_status" and "last_MQTT_Client_statusID".

Just a little post-block-call debug logic (which I nearly always do for Siemens blocks with done/error/status outputs) tells you so much about what happened during commissioning, during service calls, and during upgrades.

And #4, make sure the MQTT username & password are eXaCTly as tYPed on the MQTT server.

ND_Hung

hello everyone.
I'm using librarry FB "LMQTT_Client" for SIMATIC S7-CPU with PLC Sim advanced V2.0, but can't connect to MQTT broker. Block Mqtt client not show code error.
Librarry Link: https://support.industry.siemens.com/cs/document/109748872/fb-lmqtt_client-for-simatic-s7-cpu?dti=0&lc=en-MW 
hope the helping, thank very much.

What part of the suggestions corrected the problem you were seeing? 

ND_Hung

thank you verry much!
It has worked well