After changing different 4g routers and wifi settings, once I thought I managed to find one which works and is stable, I noticed that it works fine when the car is in Park mode. Once I switch to D or R, it instantly drops the wifi, and never reconnects by itself. If I reconnect it manually, it stays connected until I change gears ! Then again, it instantly disconnects !
I wonder if this is a bug or this is how someone from Tesla imagined this system, and if so I would like to know the reasons for such a stupid thing. I am really pissed off, I have just got tired repairing this car, I feel like driving a prototype, not a commercial product!