TCP Client(Indy10) with VPN can not detect disconnect when VPN disconnected!!

I'm use Indy10.

I can not sure TIdTCPClient is buggy or VPN Client is buggy!! The situation is:

My client work in VPN to communicate server!!

My client connect to tcp server(TIdTCPServer)  and read until server sent infinitly!!

When VPN was disconnected, TCP.GetResponse() does not throw exception like EIdDisconnected or EIdConClosedGracefully!!

Is it possible like that?

Someone tell me DON'T read wait infinitly, USE ping/pong client with server periodically!!

Is it good solution to establish valid connection ?

What about set read timeout for TIdTCPClient when TIdTCPClientGetResponse()?


Here is code:

procedure TWaitThread.Execute;
var
  TCP: TIdTCPClient;
  S1, S2: string;
begin
  inherited;

  FAbortEvent.ResetEvent;

  TCP := nil;
  try try
    while not Terminated do
    begin
      if nil = TCP then
      begin
        TCP := TIdTCPClient.Create(nil);
        TCP.ReadTimeout := 0;
        TCP.Host := FHost;
        TCP.Port := FPort;
      end;

      if not Tcp.Connected then
      try
        TCP.Connect;
      except
        FreeAndNil(TCP);
      end;
       
      if (nil <> TCP) and (TCP.Connected) then
      try
        S1 := TCP.Socket.ReadLn; // read welcome response
        TCP.Socket.WriteLn('client ' + FClientData);
        TCP.GetResponse(200); // read wait ok response
        S1 := TCP.LastCmdResult.Text.Text;

        Synchronize(DoReadyToWait);

        while not Terminated and not Application.Terminated do
        begin
          if WAIT_OBJECT_0 = WaitForSingleObject(FAbortEvent.Handle, 10) then
            Exit // Aborted
          else
          begin
            TCP.GetResponse(300); // read wait until received msg infinitly!!!  

            FData := TCP.LastCmdResult.Text.Text;
            Synchronize(DoNotify);
          end;
        end;
      except
        if nil <> TCP then
          FreeAndNil(TCP);
      end;

      Sleep(3000); // wait 3 sec, if disconnected
    end;

  except
  end;
  finally
    if nil <> TCP then
    begin
      if TCP.Connected then TCP.Disconnect;
      FreeAndNil(TCP);
    end;
  end;
end;