@Human_Imprint I'm pretty sure it only works on a local network meaning you have to be on the same Wifi network as the computer you want draw on. Please note, it's specifically for drawing and not really for remote computer management, so I'm not sure why you'd want to draw on a computer that's not even close to you. Perhaps you can explain your use case?
Also be aware you have to run Astropad on both your iPad and your computer. So you start up the desktop version, go to the app you want to draw in, then start up Astropad on your iPad. Not sure if you understood that piece, perhaps it has bearing your use case.
Hope that helps.