@witas777 said in Help set up 2 Servo MG995 for Duet3 6HC:
When I connected the GND contact in the GPIO pad with a "-" 5V power supply with a separate wire, everything worked right away!
In your case it might be OK to use a thin jumper wire to connect GNDs.
But in many cases it's better to connect GNDs directly between the power supplies with a thick wire. (search: usb cable melting )
Don't do both, because you might create a ground-loop which can cause other problems