[milankragujevic]

I did this for my parents. I got a RasPi 3 and a 3G modem, and setup remote management so I can check modem parameters remotely, even if the Internet is completely dead (using the 3G modem as an out of band connection).

I setup a VPN client on the 3G interface since there's no public IP address, and I connect to it from my own home network as a local IP address (which can't actually access my network due to explicit firewall rules I setup).

This way I can reboot the modem remotely even if the Internet is dead, and I also setup the Pi to reboot itself every night at 3am, in case something goes wrong and the VPN client crashes.

[_lol]

Hi Milan, would you be able to share more about how you setup the VPN client on the 3G interface?

[milankragujevic]

Yes, since it's a "modern" modem, it appears as a RNDIS ethernet interface. My VPN server's IP is constant, so I just set a default route to my VPN server's IP over 192.168.8.1 which is default Huawei mobile broadband gateway IP.