I have move the external compass away from the electronics ( about 15cm), still no change. I will try calibrating the compass on an openfield this weekend, but i tried that before with no succes. In addition i ordered an APM 2.6 plugged the GPS and compass in and everything works fine (used a different compass for the APM, no worries I did not mess the cables up).
Yesterday i upgraded the firmware, now i am able to select from 3 compasses, but i still dont have a clue which one is which one..
I also am using Windows 10 and the newest version of missionplanner