How can player hot join in middle of the Networking lobby game?

Now,with the Network system in Unity 5.4,I can create a host by “LobbyManager.matchMaker.CreateMatch”,and become a client by “LobbyManager.matchMaker.JoinMatch”.
But when the game is started and I try to join the game,I would only get “MatchMakingClient DropConnection” and fail to join the game.
Does this problem fixed in new Unity version or should I find a new way to develop a mutiplayers game witch supports “hot join”?

When you using LobbyManager to create a game, no client can join it later.Because the base class of LobbyManager, NetworkLobbyManager, has overridden OnServerConnect method of NetworkManager.
Check the source code line 257.
After deleted those lines and rewrote something, I ran the “Lobby” project again and clients can join the game in the middle.
I have posted my rewrote scripts in the forum. Since the designers of this lobby is preventing ‘hot join’, Im not sure whether you will meet more problems after your client join the lobby game in this way.