Hi ArenMook and junjettrasmonte,
I ran into the same problem and wanted to make sure you guys (especially junjettrasmonte) solved it similar :
Its theoretically possible that our game runs with multiple servers in one lan, since each player can be a server.
The implementation is still quite basic, the join menu is not much more than the TNet example. I could not find the TNUdpLobbyServer script on any gameobject (so its hard to enable or disable the it), but the lobby still seams to work fine. I only got the previously described error with the lobby servers overwriting each-other.
I solved the problem by simply removing line 194 in TNServerList.cs ( list.Clear(); ). That way the list does not get cleared before receiving a new list from another lobby server so that multiple lobby servers are working.
I don't like this approach since I had to manipulate a TNet script, but I don't see any other way. The lobby servers are on only for a short time. When a second player joins, the game gets private immediately, the client can go offline any time so the lobby server would have to change. Since I have to choose to use a local or a remote lobby server on starting a game server (TNServerInstance.Start), it would mean I would have to restart a game server whenever the lobby server goes offline, besides the trouble of synchronizing the whole operation.
I hope I could make myself clear. Maybe you guys have a better approach for this problem and are willing to share it with me

!?