Devices vs. gateways

• A gateway is hardware (e.g. an ESP32) that reads local sensors over RS485/Modbus/GPIO/I²C and forwards their data. Use it when your sensors can't reach the internet on their own.
• A direct MQTT device (mqtt-direct) connects straight to our broker with its own credentials. Use it when the device has its own network stack.

Both show up under Devices; gateway-mediated devices are nested under their gateway. Which protocol you pick when adding a device decides which path it uses.