Sometimes losing connection to ZT network when Android device changes from WiFi to cellular

[mhanuszh]

I'm not sure if this is related to these: #781, #1549

My device: Nokia 9, Android 10 My ZT client version: 1.12.0-3

(Re)Connecting to the ZT network using WiFi or cellular always works. Switching from WiFi to cellular ALMOST ALWAYS causes ZT to lose connection. Switching from cellular to WiFi does NOT causes ZT to lose connection, it even restores the connection if it's in a "bad state".

Until now, I wasn't really using ZT from my phone, so I don't know how long it has been broken, but it's not a recent bug.