fgm24/Assets/Scripts/Multiplayer/NetworkedGameSetup.cs

using System;
using System.Collections;
using System.Collections.Generic;
using Unity.Netcode;
using UnityEngine;
using UnityEngine.SceneManagement;

public class NetworkedGameSetup : NetworkBehaviour
{
    [SerializeField] private GameObject PlayerPrefab;

    private void Start()
    {
        DontDestroyOnLoad(this);
        NetworkManager.Singleton.SceneManager.OnLoadEventCompleted += SceneLoaded;
    }

    private void SceneLoaded(string sceneName, LoadSceneMode loadSceneMode, List<ulong> clientsCompleted, List<ulong> clientsTimedOut)
    {
        if (IsHost && sceneName == "Multiplayer")
        {
            for (int i = 0; i < clientsCompleted.Count; i++)
            {
                GameObject player = Instantiate(PlayerPrefab, Vector2.up * 3, Quaternion.identity);
                player.GetComponent<NetworkObject>().SpawnAsPlayerObject(clientsCompleted[i], true);
            }
        }

        NetworkManager.Singleton.SceneManager.OnLoadEventCompleted -= SceneLoaded;
    }
}