I really dunno how Nitrado works, but I think you're buying a 2x2 server, with 1 freeport. So, you can only join to the server by the freeport and, after that, you'll be able to move around the 4x4 map. Almost this is how a server works normally...
Have the same issue. I'm trying to host an own server using ASC, created a 4x4 server and open all ports but, when players try to connect, received a conection timeout error at primal_gamedata_BP. Redis ports are opened too so... dunno know what is happenning... :S