PacketManager.cs

public class PacketManager : MonoBehaviour
{
    [SerializeField]
    string address;

    [SerializeField]
    int port;

    [SerializeField]
    uint mySelfId = 0;

    [SerializeField]
    GameObject mySelfObject = null;

    [SerializeField]
    GameObject enemyPrefab = null;

    Dictionary<uint, GameObject> players;

    Socket socket;
    IPEndPoint serverEndPoint;

    byte[] data;

    // Start is called before the first frame update
    void Start()
    {
        players = new Dictionary<uint, GameObject>();
        players[mySelfId] = gameObject;
        socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        serverEndPoint = new IPEndPoint(IPAddress.Parse(address), port);
        socket.Blocking = false;

        data = new byte[16];
    }

    // Update is called once per frame
    void Update()
    {
        for (int i = 0; i < 100; i++)
        {
            int rlen = -1;
            try
            {
                rlen = socket.Receive(data, data.Length, SocketFlags.None);
            }
            catch
            {
                break;
            }

            if (rlen == 16)
            {
                uint playerId = BitConverter.ToUInt32(data, 0);
                float playerX = BitConverter.ToSingle(data, 4);
                float playerY = BitConverter.ToSingle(data, 8);
                float playerZ = BitConverter.ToSingle(data, 12);

                if (playerId == mySelfId)
                    continue;

                Vector3 playerPosition = new Vector3(playerX, playerY, playerZ);

                if (!players.ContainsKey(playerId))
                {
                    GameObject newPlayer = GameObject.Instantiate(enemyPrefab, playerPosition, Quaternion.identity);
                    newPlayer.GetComponentInChildren<TextMesh>().text = playerId.ToString();
                    players[playerId] = newPlayer;
                }
                else
                {
                    players[playerId].transform.position = playerPosition;
                }
            }
        }

        Vector3 myPosition = mySelfObject.transform.position;

        byte[] dataId = BitConverter.GetBytes(mySelfId);
        byte[] dataX = BitConverter.GetBytes(myPosition.x);
        byte[] dataY = BitConverter.GetBytes(myPosition.y);
        byte[] dataZ = BitConverter.GetBytes(myPosition.z);

        dataId.CopyTo(data, 0);
        dataX.CopyTo(data, 4);
        dataY.CopyTo(data, 8);
        dataZ.CopyTo(data, 12);

        socket.SendTo(data, data.Length, SocketFlags.None, serverEndPoint);

    }
}