We flashed the ardusub raspbian image on to the raspberry pi, however we found the IP address on the pi to be 169.254.144.82 ( Subnet mask 255.255.0.0) which is different from the manual IP: 192.168.2.2 ( Subnet mask 255.255.255.0).
We tried to change the surface computer IP to 169.254.144.81 ( Subnet mask 255.255.0.0) to match the Pi, but QGC cannot detect the Pixhawk.