I have now for 3 weeks a phantom 3 Advanced and it's working great. I bought it from an another owner that used it only 19 flights, Most of the flights was before house just takeoff. When I go over 800m (Open field) the aircraft got weaksignal and disconnect, When I go to a field in the city and go up to 200m it also disconnect. How to fix this? Antennas is in good position. Drone is flying good.