I'll be quick on this, since I'm away. Hopefully it'll help someone. I'll edit it properly in the weeks ahead.
So, I needed to connect to internet via USB tethering. Here's how I do it.
sys-usb and sys-net to be handled together, but separately.sys-usb, preferably based on minimals, thus reducing attacking surface.sys-usb is a-must disposable for security reasons.Settings->Advanced tab "Provides network" is checked. Let's call that qube - sys-usb-teth.sys-usb-teth and restart the qube to bring it to clean state for security reasons."Portable hotspot" setting, don't turn it on, but only "USB tethering" option.sys-usb-teth terminal now run$ sudo NetworkManager
Yes, with privileges.
Now check if it's working by running there for example
$ ping 8.8.8.8
If everything is OK, proceed to
I have created sys-firewall-teth based also on disposable minimal template. Start it and set its NetVm sys-usb-teth.
sys-whonix-teth, and set its netvmsys-firewall-teth.dispVM and set for its netVM either sys-whonix-teth, or sys-firewall-teth (tor or clearnet)Everything should work flawlessly.
After you finish, disconnect phone and don't forget to restart sys-usb-teth before attaching again external devices to it, in order to bring it to clean state for the devices.