Почти через улицу !!! (Брюховецкая)
Сколько мог собрать инфы: Эта штука через динамический IP с любым MQTT-сервером работает.
А здесь описано как настроить на прозрачный MQTT-шлюз https://www.zlan-iot.com/document/MQ...to_Modbus.html

В моих проектах этого вполне достаточно:
Here are the configuration instructions:

1) Server domain name or IP: the IP of the MQTT server is entered here, up to 30 characters.

2) User name: is the user name of the MQTT server.

3) Password: is the user's login password.

4) Client ID: is the client ID of MQTT.

5) Subscription topic: this is the topic that this device subscribes to. When other devices publish this topic, the server will issue it to this device. If you're just publishing, you don't usually need to fill out this field.

6) Publish topic: the topic of the data that this device sends to the server when it is serialized to MQTT.

7) MQTT advanced parameters: used to configure advanced parameters.

8) Save MQTT Settings: click this button to save after the design is completed, and then click the "download button" in the webpage download directory to download.