Also I think nova only allows two connections from the same IP if you are using a single IP from a router.
The fix would to change certain settings in the game.cfg file
mpnovaworldportmin = "32768"
mpnovaworldportmax = "32787"
mpnovaworldportdelta = "1"
mpnovaworldportrandom = "1"
mpnovaworldlanenumsessionportmin = "32768"
mpnovaworldlanenumsessionportmax = "32787"
mpnovaworldlanenumsessionportdelta = "1"
mplanserverportmin = "32768"
mplanserverportmax = "32787"
mplanserverportdelta = "1"
mplanclientportmin = "32768"
mplanclientportmax = "65535"
mplanclientportdelta = "1"
mplanclientportrandom = "0"
mplanservertojoinportmin = "32768"
mplanservertojoinportmax = "32787"
So in order to have 3 or more connect at one time you will need to change the 32768 port to another port number. Example on 3rd machine change them to 32770.
5th machine change to 32772 and so on.
Otherwise when you try to login the game will simply kick you from novaworld.