diff --git a/Modbus.Net/Modbus.Net/ComConnector.cs b/Modbus.Net/Modbus.Net/ComConnector.cs
index 42a9b19..ecc0329 100644
--- a/Modbus.Net/Modbus.Net/ComConnector.cs
+++ b/Modbus.Net/Modbus.Net/ComConnector.cs
@@ -456,6 +456,7 @@ namespace Modbus.Net
             catch (Exception err)
             {
                 Log.Error(err, "Com client {ConnectionToken} send msg error", ConnectionToken);
+                Dispose();
             }
             RefreshSendCount();
         }
diff --git a/Modbus.Net/Modbus.Net/TcpConnector.cs b/Modbus.Net/Modbus.Net/TcpConnector.cs
index 2787698..f6ee3f7 100644
--- a/Modbus.Net/Modbus.Net/TcpConnector.cs
+++ b/Modbus.Net/Modbus.Net/TcpConnector.cs
@@ -199,7 +199,7 @@ namespace Modbus.Net
             catch (Exception err)
             {
                 Log.Error(err, "Tcp client {ConnectionToken} send exception", ConnectionToken);
-                CloseClientSocket();
+                Dispose();
             }
         }
 
@@ -225,6 +225,7 @@ namespace Modbus.Net
             {
                 while (!_taskCancel)
                 {
+                    if (_socketClient == null) break;
                     NetworkStream stream = _socketClient.GetStream();
                     var len = await stream.ReadAsync(_receiveBuffer, 0, _receiveBuffer.Length);
                     stream.Flush();
@@ -298,11 +299,14 @@ namespace Modbus.Net
                 Controller.SendStop();
                 Controller.Clear();
                 ReceiveMsgThreadStop();
-                if (_socketClient.Connected)
+                if (_socketClient != null)
                 {
-                    _socketClient?.GetStream().Dispose();
+                    if (_socketClient.Connected)
+                    {
+                        _socketClient?.GetStream().Dispose();
+                    }
+                    _socketClient?.Close();
                 }
-                _socketClient?.Close();           
             }
             catch (Exception ex)
             {
diff --git a/Modbus.Net/Modbus.Net/UdpConnector.cs b/Modbus.Net/Modbus.Net/UdpConnector.cs
index 30682af..dae4717 100644
--- a/Modbus.Net/Modbus.Net/UdpConnector.cs
+++ b/Modbus.Net/Modbus.Net/UdpConnector.cs
@@ -180,7 +180,7 @@ namespace Modbus.Net
             catch (Exception err)
             {
                 Log.Error(err, "Udp client {ConnectionToken} send exception", ConnectionToken);
-                CloseClientSocket();
+                Dispose();
             }
         }
 
@@ -206,6 +206,7 @@ namespace Modbus.Net
             {
                 while (!_taskCancel)
                 {
+                    if (_socketClient == null) break;
                     var receive = await _socketClient.ReceiveAsync();
 
                     var len = receive.Buffer.Length;
@@ -265,20 +266,19 @@ namespace Modbus.Net
                 Controller.SendStop();
                 Controller.Clear();
                 ReceiveMsgThreadStop();
-                if (_socketClient.Client.Connected)
+                if (_socketClient != null)
                 {
-                    _socketClient?.Client.Disconnect(false);
+                    if (_socketClient.Client?.Connected == true)
+                    {
+                        _socketClient.Client.Disconnect(false);
+                    }
+                    _socketClient.Close();
                 }
-                _socketClient?.Close();
             }
             catch (Exception ex)
             {
                 Log.Error(ex, "Udp client {ConnectionToken} client close exception", ConnectionToken);
             }
-            finally
-            {
-                _socketClient = null;
-            }
         }
     }
 }
\ No newline at end of file