VPN is an abbreviation for „Virtual Private Network“. The aLobby supports this to setup a network between the players for Settlers 3 games. The players are connected to each other as if they were in a common network, as you know it from LAN parties.
properties
Each player receives exactly one VPN key. This is automatically downloaded and installed when the aLobby is started. The player doesn't have to do anything else.
Each player receives an IP address in the range 10.3.x.x. when setting up the VPN connection.
For the VPN connection the free software openVPN is used, which should be installed with the aLobby installation.
The VPN connection is automatically started by the aLobby when the program is started.
This automatism can be deactivated in the settings. Then you have to start the VPN connection manually before entering a game by clicking on the button in the aLobby.
The VPN connection is established to the Siedler3.net community server on which the server-side component is running.
Advantages
Less interference from unstable Internet connections.
Own network, which is also only used for the aLobby.