There is no single guide that I know of. You don’t say if the ‘one user’ is accessing remotely or is connecting over your local lan.
You will also need to know the port that your web server is ‘listening’ on.
Essentially, if your user is accessing remotely, there are 2 ways ….
Option A - Port forwarding (not recommended, as least secure)
Your ISP (internet service provider) must have assigned you a routable public IP. If you are using a normal domestic retail SIM, then this will NOT have a routable public IP, and this option is not available to you.
This will work for a public or private IP WAN address, depending what type of VLAN setup you use. Normally, you won’t have to do any sort of port forwarding. The vlan will connect your Teltonika with the user, and is able to give the user visibility of your webserver. This setup takes a little bit longer and if your ISP’s address isn’t a public routable one, can be a little more challenging.
You could use Wireguard if you have a public IP, and Zerotier if you don’t. There are other VPN’s that you could also choose to use.
Could you please clarify how you intend to access your server? Specifically, should it be reachable only from devices within the same LAN, or does it also need to be accessible remotely?
This information will help me provide more accurate and relevant guidance for your setup.