QGC communicated wth px4 through USB port and WIFI module EPS8266 but got "Communication lost" frequently

QGroundControl
1

Hi all,
I connected pixhawk2.4.8( with the Firmware of PX4) to WIFI module EPS8266 through USB port.
Then EPS8266 publish messages(char * data from the UART of pixhawk2.4.8) on topic “Vehicle” to MQTT server and subscribe messages(QByteArray buffer from the QGC station) on topic “QGC” from MQTT server.
At the same time QGC publish messages(QByteArray buffer from the QGC station) on topic “QGC” to MQTT server and subscribe the messages(char * data from the UART of pixhawk2.4.8 published by EPS8266) on topic “Vehicle” from MQTT server.

But QGC prompted “Vehicle 1 did not respond to request for parameters.This will cause %2 to be unable to display its full user interface.”
And QGC prompted “Communication lost” frequently.

Is there anyone can help me to fix it?

Thanks&Best Regards