Custom Manager script

using UnityEngine;
using System.Collections;
using UnityEngine.Networking;
using UnityEngine.UI;
 
public class NetworkManager_Custom : NetworkManager {
 
    [SerializeField] Vector3 playerSpawnPos;
    [SerializeField] GameObject Helicopter;
    [SerializeField] GameObject Soldier;
 
    bool soldier = true,helicop = true;
 
    GameObject choosenCharacter; // Helicopter or Soldier
 
 
    public void HelicopterChoose()
    {
        if (helicop) {
            choosenCharacter = Helicopter;
            playerSpawnPos = new Vector3 (-112.7f, 4f, -121.4f);
            helicop = false;
            JoinGame ();
        }
    }
 
    public void SoldierChoose()
    {
        if (soldier) {
            choosenCharacter = Soldier;
            playerSpawnPos = new Vector3 (0f, 0f, 0f);
            soldier = false;
            JoinGame ();
        }
    }
        
    public void StartupHost()
    {
        SetPort();
        NetworkManager.singleton.StartHost ();
    }
 
    public void JoinGame()
    {
        SetIPAddress ();
        SetPort ();
        NetworkManager.singleton.StartClient ();
    }
        
    void SetIPAddress()
    {
        string ipAdress = GameObject.Find ("InputFieldIPAddress").transform.FindChild ("Text").GetComponent<Text> ().text;
        NetworkManager.singleton.networkAddress = ipAdress;
 
    }
 
    void SetPort()
    {
        NetworkManager.singleton.networkPort = 7777;
    }
 
    void OnLevelWasLoaded(int level)
    {
        if (level == 0) {
 
            SetupMenuSceneButton ();
        }
    }
        
    void SetupMenuSceneButton()
 
    {
        GameObject.Find ("ButtonStartHost").GetComponent<Button> ().onClick.RemoveAllListeners ();
        GameObject.Find ("ButtonStartHost").GetComponent<Button> ().onClick.AddListener (StartupHost);
 
        GameObject.Find ("ButtonHelicoppter").GetComponent<Button> ().onClick.RemoveAllListeners ();
        GameObject.Find ("ButtonHelicoppter").GetComponent<Button> ().onClick.AddListener (HelicopterChoose);
 
        GameObject.Find ("ButtonSoldier").GetComponent<Button> ().onClick.RemoveAllListeners ();
        GameObject.Find ("ButtonSoldier").GetComponent<Button> ().onClick.AddListener (SoldierChoose);
 
    }
        
    public override void OnServerAddPlayer(NetworkConnection conn, short playerControllerId) {
 
        var player = (GameObject)GameObject.Instantiate(choosenCharacter, playerSpawnPos, Quaternion.identity);
 
        NetworkServer.AddPlayerForConnection(conn, player, playerControllerId);
    }
}