UNET NetworkServer.connections returns null

I’m just trying to get a simple script to display all current connections to the server with a simple

    foreach(NetworkConnection n in NetworkServer.connections){
       GUILayout.Label(n.connectionId.ToString());
    }

but all I get is the error

NullReferenceException: Object reference not set to an instance of an object
NetManager.OnGUI () (at Assets/Scripts/NetManager.cs:53)

So all I can assume is that Unity is not adding connections to the array. Does anyone know of a fix or is this a bug?

foreach(NetworkConnection n in NetworkServer.connections){
if (n == null) continue;
GUILayout.Label(n.connectionId.ToString());
}