System.Security.SecurityException: Методы ECall должны быть упакованы в системном модуле.
     в WindowsFormsApplication6.Form1.button1_Click(Object sender, EventArgs e)

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using UnityEngine;
using UnityEditor;

namespace WindowsFormsApplication6
{
      public partial class Form1 : Form
      {
          public string connectToIP = "127.0.0.1";
          public int connectPort = 25000;

          public Form1()
          {
              InitializeComponent();
          }

          private void button1_Click(object sender, EventArgs e)
          {
              try
              {
                  UnityEngine.Network.InitializeServer(32, connectPort, true);
                  msg("Сервер успешно запущен");
              }
              catch (Exception ex)
              {
                  msg("Не удается запустить сервер по причине - " + ex);
              }
          }

          void msg(string message)
          {
              listBox1.Items.Add(message);
          }
      }
}