ardxp.ino is an empty template. To use it you will need to figure out the datarefs and commands that your interface needs and add code to subscribe to datarefs, send new dataref values to X-Plane, or ...

Each arduino board has own code, For the 1st arduino board load the 111-ip code. Once the code already uploaded into the board, check the serial monitor if the ip address is 111.111.111.111. For 2nd ...