My software/library limits MQTT client ID to 23 characters, what should I do?

MQTT’s specifications state The Server MUST allow ClientIds which are between 1 and 23 UTF-8 encoded bytes in length and The Server MAY allow ClientId’s that contain more than 23 encoded bytes. Certain software/libraries restrict MQTT client ID field to 23 characters max.

If you fall into this situation, you can type your Device ID in the MQTT Username field. If no valid Device ID is found in the MQTT client ID field but one is found in the MQTT Username field, the one found in the Username field will be used as client ID.