请教高手在局域网能够通连，但是太远了就出问题！！

我做了一个简单的连接程序，使用ServerSocket和ClientSocket控件，我在局域网、校园网以及同一城市内都可以互连， 但是太远了就显示报错， 是什么地方出了问题，请教各位！！

客户端简单连接程序：

procedure TfrmClientMain.tbConnectedClick(Sender: TObject);
begin
ClientSocket.Open ;
end;
procedure TfrmClientMain.tbDisconnectedClick(Sender: TObject);
begin
ClientSocket.Close;
end;
//接受服务器端的回复
procedure TfrmClientMain.ClientSocketRead(Sender: TObject;
Socket: TCustomWinSocket);
begin
Memo1.Lines.Add(Socket.ReceiveText);
end;
//发送信息到服务器端
procedure TfrmClientMain.tbSendClick(Sender: TObject);
begin
ClientSocket.Socket.SendText(Edit1.Text);
end;
procedure TfrmClientMain.tbCloseClick(Sender: TObject);
begin
Close;
end;

//已经连接到服务器端
procedure TfrmClientMain.ClientSocketConnect(Sender: TObject;
Socket: TCustomWinSocket);
begin
tbSend.Enabled := True;
tbDisconnected.Enabled :=True;
btnSend.Enabled := True;
StatusBar.Panels[0].Text := '已经连接到 '+ Socket.RemoteHost ;
end;

//正在连接到服务器端
procedure TfrmClientMain.ClientSocketConnecting(Sender: TObject;
Socket: TCustomWinSocket);
begin
StatusBar.Panels[0].Text := '正在连接到服务器... ' ;
end;

//当断开与服务器端的连接时发生
procedure TfrmClientMain.ClientSocketDisconnect(Sender: TObject;
Socket: TCustomWinSocket);
begin
tbSend.Enabled := False;
btnSend.Enabled := False;
tbDisconnected.Enabled := False;
StatusBar.Panels[0].Text := '已经断开与 '+ Socket.RemoteHost +' 的连接';
end;
procedure TfrmClientMain.FormClose(Sender: TObject;
var Action: TCloseAction);
begin
ClientSocket.Close ;
end;
//当与服务器端的连接发生错误时
procedure TfrmClientMain.ClientSocketError(Sender: TObject;
Socket: TCustomWinSocket; ErrorEvent: TErrorEvent;
var ErrorCode: Integer);
begin
StatusBar.Panels[0].Text := '与服务器端的连接发生错误';
ErrorCode := 0;
end;
procedure TfrmClientMain.ToolButton1Click(Sender: TObject);
var
inputstring:string;
begin
inputstring:=inputbox('输入','输入主机ip地址：','') ;
tbConnected.Enabled:=true;
ClientSocket.Host:=inputstring;
end;





服务端简单连接程序：
procedure TForm1.Button1Click(Sender: TObject);
begin
serversocket1.Active:=true;
end;

procedure TForm1.ServerSocket1Listen(Sender: TObject;
Socket: TCustomWinSocket);
begin
label1.Caption:='等待客户端连接....................';
end;

procedure TForm1.ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
begin
Memo1.Lines.Add(Socket.ReceiveText);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
serversocket1.Socket.Connections[0].SendText(edit1.Text);
end;

procedure TForm1.ServerSocket1ClientConnect(Sender: TObject;
Socket: TCustomWinSocket);
begin
label1.Caption:='连接成功';
end;