Connection to Navio/Rpi4 to Mission planner using SSH

I have updated the card and I can connect to ardupilot but in the correct way I think.

Here is how I do it :

cd arducopter  
sudo /home/pi/ardupilot/build/navio2/bin/arducopter -A udp:<IP_OF_MY_ PC>:14550  

Then when I open Mission planner it connects automatically on UDP14550-1-QUADROTOR. I have access to telemetry info and can caliber the accel and compass.
If I disconnect to dowload the firmware (which also doesnt’t work : Failed to detect port to upload to (Unkwon VID/PID or Board String)).
I can’t reconnect through mission planner.

I also try to plug a usb cable on the Rpi4 and an ethernet cable but my PC doesn’t seem to recognized the board.

What can I do next ?