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MQTT connection problems

 Q: Connection problems with MQTT

A: Check first the TLS /Cypher combination for your modem and (web)server.

If TLS and Cyphers are matching the website, there could be other problems.

1) Some Brokers are not “Generic” but part of an IoT platform. They don’t allow free choice of topic names or subscription. In that case, in the Data Logger, the configured “root-topic” has to match the obliged “root-topic” name in the IoT platform. Only the Data Log File can be sent. Configure “Omit Subtopics” and “Clean-Session”.

2) If a data logger establishers a connection (throug TLS /SSL) to the (web)server, but can’t deliver the data (connection is broken), then check for access rights.

  • Only authorized client ID’s are allowed, configure this client ID into the Data Logger
  • The Data Logger has no publish or subscripe rights to certain topics. Grant access to to “#” or at least “YDOC/#”

3) If a data logger establishes a connection (throug TLS /SSL) to the (web)server, but the connection is broken before the data delivery completes. This could be a timing issue on the (web)server. Some (web)server administrators are decreasing the standard connection time-out to prevent unwanted connections or performance issues. The only way to solve this problem is asking the (web)server administrator to increase the time-out to a standard value. (about 4 seconds).

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