Version: 2018.1
public static int maxConnections ;

Description

Set the maximum amount of connections/players allowed.

Setting it to 0 means no new connections can be made but the existing ones stay connected. Setting it to -1 means the maximum connections count is set to the same number of current open connections. In that case, if a players drops then the slot is still open for him. This cannot be set higher than the connection count given in Network.InitializeServer.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { void StartGameNow() { Network.maxConnections = -1; } }