It's the same as any other multiplayer game. If you start a server, you basically make it possible for others to join -- however unless you give them your address, they won't be able to find you. You can make your server discoverable by the network if you wish, or you can register with a remote lobby server. Your original question was about what options you have for the server. There is only one option -- you start it, and there you go. The only options you have is for its discovery. No discovery (by doing nothing), LAN discovery (using TNUdpLobbyClient), or WAN discovery by registering with a remote lobby server that's hosted somewhere accessible (basically 3rd party).
ExampleMenu.cs script that comes with TNet handles all this for you. For example, this is the code that starts the server:
int udpPort = Random.Range(10000, 40000);
TNLobbyClient lobby = GetComponent<TNLobbyClient>();
if (lobby == null)
{
TNServerInstance.Start(serverTcpPort, udpPort, "server.dat");
}
else
{
TNServerInstance
.Type type
= (lobby
is TNUdpLobbyClient
) ? TNServerInstance.Type.Udp : TNServerInstance.Type.Tcp;
TNServerInstance.Start(serverTcpPort, udpPort, lobby.remotePort, "server.dat", type);
}
So depending on which Lobby Client you have attached, it will either have no discovery at all (lobby is null), UDP discovery (LAN) or TCP discovery (WAN, remote server).
