I love KDE connect. It makes smartphone interaction really seamless. However, it only works in the same wifi (most likely some wifi you control).
PS: Just noticed there is a VPN feature https://userbase.kde.org/KDEConnect#Running_KDE_Connect_over... -- KDEconnect is really amazing.
You can share links and files with any connected device. Use it as a remote control for music players and presentations. Ring your phone from your computer to find it and more.
https://kdeconnect.kde.org/
(edit: add second paragraph and link)