HTTP/Socket cannot co-exist only on Symbian

I use QNetworkAccessManager to request http service and use QTcpSocket to keep socket connection.
But If make http request,socket will disconnect.

Please check attached project. I tested it on N8 and Symbian Belle device.
Steps:
1. Click "connect to server" button to start http to request server IP and port: LoginController->login().
2. LoginController->http_finish will get IP and port.
3. ServiceManager::getInstance()->conectToServer() make one tcp socket connection to server
4. TCP succeed, but disconnection directly.

I logged error code:
QAbstractSocket::NetworkError 7
An error occurred with the network (e.g., the network cable was accidentally plugged out).

And before step 3, I tried 'delete http' first, then socket works well. But the requirement needs HTTP/Socket co-exist.

The code works well on Qt Simulator and N9.