diff --git a/src/bluetooth/qlowenergycontroller_bluez.cpp b/src/bluetooth/qlowenergycontroller_bluez.cpp
index 9435d479..5cb18678 100644
--- a/src/bluetooth/qlowenergycontroller_bluez.cpp
+++ b/src/bluetooth/qlowenergycontroller_bluez.cpp
@@ -3034,7 +3034,15 @@ void QLowEnergyControllerPrivate::handleConnectionRequest()
         qCWarning(QT_BT_BLUEZ) << "Received client connection, but no connection complete event";
 
     closeServerSocket();
+
+    if (l2cpSocket) {
+        // old instance .. maybe relese some resources ??
+        delete l2cpSocket;
+        l2cpSocket = nullptr;
+    }
     l2cpSocket = new QBluetoothSocket(QBluetoothServiceInfo::L2capProtocol, this);
+    int tmp_fd = l2cpSocket->socketDescriptor();    // tmp file descriptor, it will be overwritten with: l2cpSocket->setSocketDescriptor
+
     connect(l2cpSocket, &QBluetoothSocket::disconnected,
             this, &QLowEnergyControllerPrivate::l2cpDisconnected);
     connect(l2cpSocket, static_cast<void (QBluetoothSocket::*)(QBluetoothSocket::SocketError)>
@@ -3047,6 +3055,12 @@ void QLowEnergyControllerPrivate::handleConnectionRequest()
     restoreClientConfigurations();
     loadSigningDataIfNecessary(RemoteSigningKey);
 
+    qCDebug(QT_BT_BLUEZ) << __FUNCTION__ << "open client socket: " << l2cpSocket->socketDescriptor();
+    if (0 < tmp_fd && (tmp_fd != l2cpSocket->socketDescriptor()))
+        qCDebug(QT_BT_BLUEZ) << __FUNCTION__ << "close old socket: " << tmp_fd;
+        if (close(tmp_fd) < 0)  // close unused descriptor
+            qCWarning(QT_BT_BLUEZ) << __FUNCTION__ << "close client socket error: " << qt_error_string(errno);
+
     Q_Q(QLowEnergyController);
     setState(QLowEnergyController::ConnectedState);
     emit q->connected();
@@ -3057,7 +3071,9 @@ void QLowEnergyControllerPrivate::closeServerSocket()
     if (!serverSocketNotifier)
         return;
     serverSocketNotifier->disconnect();
-    close(serverSocketNotifier->socket());
+    qCDebug(QT_BT_BLUEZ) << __FUNCTION__ << "close socket: " << serverSocketNotifier->socket();
+    if (close(serverSocketNotifier->socket()) < 0)
+        qCWarning(QT_BT_BLUEZ) << __FUNCTION__ << "close socket error: " << qt_error_string(errno);
     serverSocketNotifier->deleteLater();
     serverSocketNotifier = nullptr;
 }