I have a 4G modem (E3372) that only automatically connects/dials if I:

1. Have it inserted on bootup.
2. Insert it after bootup, but only once.

I wan't to be able to powercycle the USB-port but can't get it to work at the moment. Is there a way to reset all USB / ppp state without rebooting?

I have tried to disable / enable the ppp interface but it only reconnects if [1] and [2] is true. If I have removed / inserted or power cycled the USB port it won’t reconnect.

951G-2HnD
Current Firmware 3.33
Upgrade Firmware 6.43.4

How far do you want to extend? What is your requirement for WIFI speed?

Current Firmware 3.33
Upgrade Firmware 6.43.4

I'd upgrade firmware and then check things again. Firmware version 3.33 is pretty old.
and reboot.