Identify how server routs external connection into local 10.1.0.* address
This computer is most likely an OpenVPN server, as well as an Apache web server.
The clients create a secure VPN to this server and then open the initial web page, once the server becomes accessible via the VPN.
The IP address of 10.1.*.* is typical for the secure network that is
created by the VPN client, appearing on the client computer as
a virtual network adapter.
You will need to learn both OpenVPN and Apache and examine their configuration files, to better understand this setup.