Python MQTT for Data-Driven Engineering 

MQTT is probably better for your application because the connection may be unreliable. OPC requires a reliable connection and MQTT is built for IoT applications.

The Teltonika FMB920 can transmit data using LTE or via a local gateway using a Raspberry Pi. For LTE, ensure the micro-SIM is active and configure the device with network and MQTT settings to send data directly to an MQTT broker over the internet. Alternatively, use a Raspberry Pi as a local gateway by enabling Bluetooth on both devices for local data transfer, and configure the Raspberry Pi to send this data to an MQTT broker using installed MQTT client software. This setup not only allows flexibility based on connectivity and mobility needs but also the possibility of integrating additional processing capabilities through the Raspberry Pi.

In MQTT (Message Queuing Telemetry Transport), topics are used as the routing information for messages, and clients subscribe to these topics to receive messages that interest them. However, MQTT does not have a built-in feature to discover topics because it is designed to be lightweight and simple. Topics are typically determined by the application design or the configuration of the MQTT broker and its clients. If you're working with an MQTT broker and you don't know the topics, here are a few approaches you can take to discover or manage topics: Broker Configuration and Logs: Check Broker Configuration: If you have access to the MQTT broker, you can check its configuration files. Some brokers might list the topics that have been configured or have defaults. Broker Logs: Some MQTT brokers log details about connected clients and their subscriptions. By examining these logs, you might be able to identify active topics. Contact System Administrator or Developer: If you're working in a managed environment, the system administrator or the developer who set up the MQTT broker might have a list of topics or documentation about the topic structure.

and I made it port 83 ;)