Automatic connection

Hi,

I use a Raspberry pi 3 b+, and a 3G/4G LTE HAT (telit module). I configured a ppp connection that works well.
My problem is that, when i switch off the raspberry and disconnect the power supply. The connection does not work when i reconnect the power supply, (my mouse and keyboard are also freezed). I have to unplug and replug the USB cable(from the hat) in order that the ppp0 interface appears. If I use the command “sudo reboot”, the auto-connect process works well when the pi reboots.

To sum-up when I unplug the power supply, it does not reconnect automatically. Does anyone can help me to make it work.

I followed step by step, the ppp tutorial with auto-reconnect service.

Thanks