I have the exact same problem and basically the same hardware setup (QGC is updated) as the original poster, so perhaps you could help me here. I have been following the guide you linked to and here’s the file you were asking for:
(the text in bold is being preceded by a pound sign (#))
Default settings for ArduPilot for Linux.
The file is sourced by systemd from arduplane.service
Options to pass to ArduPilot
-A is a console switch (usually this is a Wi-Fi link)
-C is a telemetry switch
Usually this is either /dev/ttyAMA0 - UART connector on your Navio
or /dev/ttyUSB0 if you’re using a serial to USB convertor
-B or -E is used to specify non default GPS
Type “emlidtool ardupilot” for further help
Neither TELEM1 (wi-fi connection to my laptop) nor TELEM2 (a telemetry dongle connected to the Navio2) are working on QGC or Mission Planner. QGC is constantly sending the “Error writing to QHostAddress(”")1" message. Any ideas?
(oh, and the UDP box was already ticked in the Application Settings.)