diff --git a/DroneClient/NetClient.cs b/DroneClient/NetClient.cs
index 603c61f..27f8f61 100644
--- a/DroneClient/NetClient.cs
+++ b/DroneClient/NetClient.cs
@@ -31,6 +31,7 @@ namespace DroneSimulator
       public byte[] buffer = new byte[size];
     }
 
+    private bool Connected = false;
     private Socket? ServerSocket = null;
     private ServerData DataServer = new ServerData();
 
@@ -43,10 +44,11 @@ namespace DroneSimulator
 
     public ClientState Connect(string Addr, int Port, ClientCallback Connection, ClientCallback Receive)
     {
-      if (ServerSocket != null)
+      if (Connected)
       {
-        ServerSocket.Close();
-        ServerSocket = null;
+        try { ServerSocket?.Shutdown(SocketShutdown.Both); } catch { }
+        ServerSocket?.Close();
+        Connected = false;
         return ClientState.Stop;
       }
 
@@ -56,24 +58,26 @@ namespace DroneSimulator
       IPEndPoint ep = new IPEndPoint(IPAddress.Parse(Addr), Port);
       ServerSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 
-      try
-      {
-        ServerSocket.Connect(ep);
-      }
-      catch { ServerSocket.Close(); ServerSocket = null; return ClientState.Error; }
+      try { ServerSocket.Connect(ep); }
+      catch { ServerSocket.Close(); return ClientState.Error; }
+
+      Connected = true;
 
       ConnectionCallback(new ConnectData { Connect = true, Server = ServerSocket });
 
       ReceiveData receiveData = new ReceiveData { Buffer = DataServer.buffer, Size = ServerData.size, Server = ServerSocket };
-      ServerSocket.BeginReceive(DataServer.buffer, 0, ServerData.size, 0, new AsyncCallback(ReadCallback), receiveData);
+
+      try { ServerSocket.BeginReceive(DataServer.buffer, 0, ServerData.size, 0, new AsyncCallback(ReadCallback), receiveData); }
+      catch { }
 
       return ClientState.Connected;
     }
 
     public void Close()
     {
+      try { ServerSocket?.Shutdown(SocketShutdown.Both); } catch { }
       ServerSocket?.Close();
-      ServerSocket = null;
+      Connected = false;
     }
 
     public void ReadCallback(IAsyncResult ar)
@@ -82,23 +86,23 @@ namespace DroneSimulator
       if (cd == null) return;
 
       int bytes = 0;
-      try { bytes = ServerSocket.EndReceive(ar); }
-      catch {  }
+      try { bytes = ServerSocket.EndReceive(ar); } catch {  }
 
       if (bytes == 0)
       {
         ServerSocket?.Close();
 
-        if (ServerSocket != null) ConnectionCallback(new ConnectData { Connect = false, Server = null });
+        Connected = false;
 
-        ServerSocket = null;
+        if (ServerSocket != null) ConnectionCallback(new ConnectData { Connect = false, Server = null });
 
         return;
       }
 
       ReceiveCallback(new ReceiveData { Buffer = cd.Buffer, Size = bytes, Server = ServerSocket });
 
-      ServerSocket?.BeginReceive(cd.Buffer, 0, ServerData.size, 0, new AsyncCallback(ReadCallback), cd);
+      try { ServerSocket?.BeginReceive(cd.Buffer, 0, ServerData.size, 0, new AsyncCallback(ReadCallback), cd); }  
+      catch { }
     }
   }
 }
diff --git a/DroneSimulator/FormMain.cs b/DroneSimulator/FormMain.cs
index b7926ff..9e6489a 100644
--- a/DroneSimulator/FormMain.cs
+++ b/DroneSimulator/FormMain.cs
@@ -81,7 +81,8 @@ namespace DroneSimulator
       od.PosX= drone.PosXYZ.X; od.PosY = drone.PosXYZ.Y;
       od.LaserRange = drone.LaserRange;
 
-      data.Client.Send(od.getBytes());
+      try { data.Client.Send(od.getBytes()); }
+      catch { }
     }
 
     private void button_Client_Start_Click(object sender, EventArgs e)
@@ -102,6 +103,7 @@ namespace DroneSimulator
           }
         case NetServerClients.ServerState.Stop:
           {
+            label_Clients_Num.Text = "0";
             button_Client_Start.Text = "Start";
             button_Client_Start.BackColor = Color.Transparent;
             break;
diff --git a/DroneSimulator/NetServerClients.cs b/DroneSimulator/NetServerClients.cs
index d8ebdce..0a6384d 100644
--- a/DroneSimulator/NetServerClients.cs
+++ b/DroneSimulator/NetServerClients.cs
@@ -38,7 +38,7 @@ namespace DroneSimulator
 
     private int SocketID = 0;
     private int SocketLimit;
-    private Socket? ServerSocket = null;
+    private Socket? ServerSocket;
     private List<ClientData> ClientSockets = new List<ClientData>();
 
     public delegate void ServerCallback(object o);
@@ -46,14 +46,21 @@ namespace DroneSimulator
     private ServerCallback? ConnectionCallback;
     private ServerCallback? ReceiveCallback;
 
+    private bool Active = false;
+
     public enum ServerState { Error, Start, Stop };
 
     public ServerState StartServer(int Port, int Limit, ServerCallback Connection, ServerCallback Receive)
     {
-      if (ServerSocket != null)
+      if (Active)
       {
-        ServerSocket.Close();
-        foreach (ClientData c in ClientSockets) { c.workSocket?.Shutdown(SocketShutdown.Both); c.workSocket?.Close(); }
+        ServerSocket?.Close();
+        foreach (ClientData c in ClientSockets)
+        {
+          try { c.workSocket?.Shutdown(SocketShutdown.Both); } catch { }
+          c.workSocket?.Close();
+        }
+        ClientSockets.Clear();
         return ServerState.Stop;
       }
 
@@ -70,8 +77,9 @@ namespace DroneSimulator
         ServerSocket.Bind(ip);
         ServerSocket.Listen(10);
         ServerSocket.BeginAccept(new AsyncCallback(AcceptCallback), ServerSocket);
+        Active = true;
       }
-      catch { ServerSocket.Close(); ServerSocket = null; return ServerState.Error; }
+      catch { ServerSocket.Close(); return ServerState.Error; }
 
       return ServerState.Start;
     }
@@ -84,7 +92,7 @@ namespace DroneSimulator
       Socket handler;
 
       try { handler = listener.EndAccept(ar); }
-      catch{ ServerSocket?.Close(); ServerSocket = null; return; }
+      catch{ ServerSocket?.Close(); Active = false; return; }
 
       if (SocketLimit > ClientSockets.Count)
       {
@@ -127,7 +135,11 @@ namespace DroneSimulator
 
       ReceiveCallback(new ReceiveData { ID = cd.ID, Buffer = cd.buffer, Size = bytes, Client = cd.workSocket });
 
-      cd.workSocket?.BeginReceive(cd.buffer, 0, ClientData.BufferSize, 0, new AsyncCallback(ReadCallback), cd);
+      try
+      {
+        cd.workSocket?.BeginReceive(cd.buffer, 0, ClientData.BufferSize, 0, new AsyncCallback(ReadCallback), cd);
+      }
+      catch { }
     }
   }
 }