Cannot Connect in Mission Planner

I have problem with my Mission Planner.
I using Mission Planner 1.3.41 and Pixhawk 2.4.8.
First, I connected my Mission planner in baudrate 57600.
then I setting in full parameter
I set it to Serial Communication Pixhawk-Raspi3

SERIAL2_PROTOCOL = 1 (the default) to enable MAVLink on the serial port.
SERIAL2_BAUD = 921 so the Pixhawk can communicate with the RPi at 921600 baud.
LOG_BACKEND_TYPE = 3 if you are using APSync to stream the dataflash log files to the RPi

And I have setting several times the Serial1 Baud and Serial2 Baud.
After that, I cannot connect again to Mission Planner, I have use baudrate 57600, 921600, and 115200.

Could anyone help me, please :sweat:?