Connect 2 LTE routers through a cellular network

Thanks for reading in advance.

I want to connect 2 LTE routers (client and server). The scheme is as follows: Host A - Server Router - Cellular network - Client Router - Host B

The purpose of establishing the connection is to be able to ping through cmd or similar.

My idea is to create a VPN between both routers, but I don't know the steps to configurate them.

Can someone tell me the steps to follow to configure these routers or some alternative to be able to ping between host A and Host B?

Note 1: Both routers do not have SIM with public IP.

Note 2: The routers have VPN setting options: IPSec/PPTP/L2TP/OpenVpn/GRE Tunnel)

Solution 1:

If the devices don't have a public IP address (and assuming you don't have special support from your telco), you cant do this directly. You will need an intermediary device with a public - ideally static IP.

There are a few ways to do this. Likely the easiest way is to get both devices set up as VPN clients and use a service that can provide each client with its own static IP (but note the service can see unencrypted traffic between the 2 VPN's)

An alternative might be to run your own VPN server on a static IP - for example "in the cloud" and have both clients connect to it. This is likely more work but slightly more secure.