Hey, thanks Filipe!
Tough question IMO to be honest. I never worked too much with mobile. Some suggestions, in case you haven't tried them already:
- Try to log debug prints to a file, maybe this way you can pinpoint what the exact issue is;
- Since when running from the editor things are working OK, then maybe the smartphone itself is denying the internet access? Maybe your game needs to ask the device permission to make the API calls.
Once again, I never worked too much with mobile, so those two things are mostly guesses of mine. Good luck though!