The present disclosure provides a data transmission method, a network device, a terminal device, and a computer readable storage medium, the data transmission method including: on a first network side, providing first data to a first network address in a first network; determining, based on mapping of first network addresses in the first network and second network addresses in a second network, a second network address according to the first network address; and transmitting the first data to a terminal device located at the determined second network address in the second network based on a Message Queue Telemetry Transmission (MQTT) protocol.