[URGENT] Problem with synchronizing objects loaded from server for multiplayer

Hi guys, how to synchronize an object that is loaded from a server?

When I tried running the game with the object (simple 3d cube) placed in the hierarchy window, the objects do synchronize in the players' game. I use the Network manager HUD script. The object will spawn after choosing to be a host or joining a host.

But when I built the asset bundle of this object and upload it to a server, the object would not synchronize in the players' game and this object was spawned even before I choose to be either the host or to join a host..

Please help...

I did attach the network identity script to the object. Here is my LoadAsset script:

 using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  using UnityEngine.Networking;
  
  public class LoadAsset : MonoBehaviour {
  
      public GameObject cube;
  
      // Use this for initialization
      void Start () {
          StartCoroutine(InstantiateObject());
      }
  
      IEnumerator InstantiateObject(){
          string url = "http://192.168.137.1:8080/cube";
          UnityWebRequest request = UnityWebRequest.GetAssetBundle (url, 0);
          yield return request.Send ();
          AssetBundle bundle = ((DownloadHandlerAssetBundle)request.downloadHandler).assetBundle;
          cube = bundle.LoadAsset<GameObject> ("Cube");
          Instantiate (cube);
      }
  }