How to start vpn remotely?

Question

VPN

How can I remotely start a VPN connection on Windows Server 2012 or 2016 (updating is not a problem if necessary). The essence of the problem is that the server is hidden behind NAT and you need to connect to VPN and then connect there via RDP.
USB modems are connected to the server (Huawei E1550 and E150). Accordingly, there was an idea to implement this somehow by sending SMS to a SIM card, but I did not find the software. Please advise how to implement this.
If it is important then VPN is a normal pptp connection by login/password. Everything is saved on the server. Connection by regular means. Before that, I used a crutch in the form of a teamviewer and ran through it, but stability has begun to fail lately.

Answer 1

ngrok to forward a port to the outside world, connect to this port and execute commands.

Answer 2

You have a VPN for remote access, but in order to run something remotely, you need remote access (at least in the form of a command line).
Set the server to establish a connection automatically and reconnect when disconnected and rebooted.