@Vinnai: I am not exactly sure what you mean. Did you mean that you use your phone to remotely access OSPi / OS, or that your OSPi / OS is on a mobile (3G/4G) network? If it’s the former, please check the Port Forwarding tutorial:
https://openthings.freshdesk.com/solution/articles/5000569763-video-how-to-set-up-port-forwarding-for-remote-access