C94-M8P-2 as RTK

Hi, I am traying to use the Ublox C94-M8P-2 as RTK for my rover.
I have read some topics about it (e.g C94 m8p rtk from this forum) , and how to connect my pixhawk 4 to the C94-MP8 module , but nothing worked. I am using the mission planner as interface.
I wired Pin 9 and 10 of the Ublox to Uart&I2C of the Pixhawk.
I am little confuse with the set up in the mission planner with the serial ports. Could anybody help me with some set up?
In another hand I would like if it possible to disable the original antenna of the Pixhawk, or, is it neccesary that both antennas work together ?