Azure function app hang as MQTTnet.Exceptions.MqttCommunicationException, MQTTnet.Exceptions.MqttCommunicationTimedOutException

[nghianguyendev]

If there is exceptions regarding to connection then the azure function app will be hung.

These are exceptions:

• ‘MQTTnet.Exceptions.MqttCommunicationException : No connection could be made because the target machine actively refused it. [::ffff:13.69.85.206]:1883’ at 2020-12-22 15:26:21.4423821 UTC
• ‘MQTTnet.Exceptions.MqttCommunicationTimedOutException : Exception of type 'MQTTnet.Exceptions.MqttCommunicationTimedOutException' was thrown.’ at 2020-12-29 15:25:50.7264167 UTC

This is the information from MS support.
“Our current speculation is that, when the function was running, the target server refused the connection for some reason which caused the function code stuck in deadlock. This also leads to the function process hanging the whole time.”

Is there anyone meet this issue?