Unet: Where or when to spawn Environmental objects (OnStartServer does not work properly)

Hi there, yea i am (just for testing purposes) spawning a procedural Asteroid Field.

Hm i tested the OnServerInitialized function but it doesnt get invoked :(

Here is my spawner class. It is on a empty GO inside the scene and has a Network Identity on it.

 using UnityEngine;
 using UnityEngine.Networking;
 
 public class AsteroidField$$anonymous$$anager : NetworkBehaviour
 {
     [SerializeField]
     private int asteroids$$anonymous$$ax = 100;
     [SerializeField]
     private float asteroid$$anonymous$$axSize = 3.0f;
     [SerializeField]
     private float asteroid$$anonymous$$inSize = 1.0f;
     [SerializeField]
     private float asteroid$$anonymous$$axSpeed = 1.0f;
     [SerializeField]
     private float asteroid$$anonymous$$inSpeed = 0.0f;
     [SerializeField]
     private float asteroidDistance = 10.0f;
     [SerializeField]
     private GameObject asteroid;
 
     private float asteroidSize;
     private float asteroid$$anonymous$$ass;
     private Vector3 randomPos;
 
 
     public override void OnStartServer()
     {
         //base.OnStartServer();
         Debug.Log("Server started");
         CalculateAsteroidField();
     }
 
 
     void OnServerInitialized()
     {
         Debug.Log("Server initialized and ready");
     }
 
 
     private void CalculateAsteroidField() 
     {
         for (int i = 0; i < asteroids$$anonymous$$ax; i++) 
         {
             asteroidSize = Random.Range(asteroid$$anonymous$$inSize, asteroid$$anonymous$$axSize);
             asteroid$$anonymous$$ass = asteroidSize * 10f;
 
             asteroid.transform.localScale = Vector3.one * asteroidSize;
             asteroid.GetComponent<Rigidbody>().mass = asteroid$$anonymous$$ass;
 
             randomPos = Random.insideUnitSphere * asteroidDistance;
             
             while(Utils.CheckOverlap(randomPos, asteroid.transform.localScale))
             {
                 randomPos = Random.insideUnitSphere * asteroidDistance;
             }
 
             GameObject asteroidInstance = (GameObject)Instantiate(asteroid, randomPos, Random.rotation);
 
             asteroidInstance.name = "Asteroid" + i;
 
             if (Random.Range(0, 3) == 0)
             {
                 float randSpeed = Random.Range(asteroid$$anonymous$$inSpeed, asteroid$$anonymous$$axSpeed) * 0.5f;
 
                 asteroidInstance.GetComponent<Rigidbody>().velocity = randSpeed * asteroidInstance.transform.forward;
             }
 
             NetworkServer.Spawn(asteroidInstance);
         }
     }
 }

It kinda works but only the first time i click on "LAN Host(H)". When is stop the host and click on "LAN Host(H)" again the OnStartServer fuction doesnt get called. And unforunately the OnServerInitialized fuction doesnt get called at all. Any suggestions? Oh we are of courese talking about the Network$$anonymous$$anager and its HUD.