UNIT MQTT: unable to set MAC address

  • Hi,
    This is a question about UNIT MQTT (SKU:U129).
    I sent the following AT command to change the Unit's MAC address, but an error was returned.
    What did i do wrong?

    b'+NETMAC=ERROR:Error Param\r\n'

    Other commands can be executed, but only the MAC address cannot be set.

    <firmware version>