Why won't this basic Unet example connect?

EDIT: Wow it was the latest Beta stopping it from working. It works fine in 5.3.5.

Following this simple example: https://docs.unity3d.com/Manual/UNetClientServer.html I'm supposed to get a Connect message from just this code. I run 2 instances of the game and the server starts, so I try to connect with the other instance and...nothing happens! It continues printing every frame "client.isConnected = False". My pc is port forwarded, and the scene is just 1 empty game object with this script attached. Why can't the client connect?

Does UNET not work in the latest Unity Beta Free Version? Do I need a NetworkIdentity somewhere?

Code (JavaScript):

1. import UnityEngine.Networking;
2.  
3. private var client : NetworkClient;
4.  
5. function Update(){
6.  
7.     if(client) print(client.isConnected);
8.  
9.     //be server
10.     if(Input.GetKeyDown(KeyCode.S)){
11.         NetworkServer.Listen(7777);
12.     }
13.  
14.     //be client
15.     if(Input.GetKeyDown(KeyCode.C)){
16.         client = new NetworkClient();
17.         client.RegisterHandler(MsgType.Connect, ClientConnect);
18.         client.Connect("127.0.0.1", 7777);
19.     }
20. }
21.  
22. function ClientConnect(n : NetworkMessage){
23.     print("ClientConnect");
24. }