Cubeblack / px4 / here3 very bad precision

Hello,

I have a problem with my GPS here2/here3 on pixhawk cubeblack plugged on CAN. Gps gives me an error variation between 3 meters and 10 meters and does not stop moving.

In QGroundControl, I changed:

EKF2_AID_MASK = 1
GPS_1_CONFIG = UART6

UAVCAN_ENABLE = Sensors Automatic Config

I tried with a cubeblack (I don’t know firmware version), another cube black with last firmware (downloaded yesterday), both with here2, here3 and both pixhawk with both GPS on can1 and can2. Always same result on QGroundControl and mission planner, drone does not stop moving (only pixhawk with GPS placed on a table outside plugged to my computer with USB) and an error variation between 3 and 10 meters.

Any idea of what I did wrong ?
Thank you very much i’m new in this domain

Thank you