USB_ModeSwitch

Root access is used just by PPP, FX, and Flashr.
I don't use anything except Play store apps. Maybe it's because I rooted the device using kingroot and then replaced it with supersu and it left some sort of change?
If you want, I can set up teamviewer host on my tablet to let you remotely check what's happening.

SumTingWong wrote:Maybe it's because I rooted the device using kingroot and then replaced it with supersu and it left some sort of change?

That's a possible cause. However, if root programs get the root permission dialogue from SuperSU after the first install, then the "su" installation should be O.K.

Direct access to your device is not necessary - you could post both a "dmesg" and a "logcat -d" output file though, created immediately after a connection attempt.

Here they are.

The "logcat" looks as it should. The system accepts the network connection which is the main hurdle for user-created network interfaces: The "dmesg" however does not show anything related to a freshly plugged USB device. Are you sure you caught the moment when you plugged the modem in?

It would help to see the whole sequence of plugging the modem, preparing and connecting in the dmesg log.

This is just after starting the tablet. One dmesg before, the other after plugging in the modem and connecting.

I did not reply yet because I'm somewhat out of ideas.

In the meantime, I did some clean-up in the code for setting the default route. Did you try with the current version?