I appears that you are connecting to a host, which you already connected earlier.

What will happen if MyThread::readReady() is called twice? ...Yes, you will try connecting to host which is already connected (or trying to connect becasue of the first call to readReady()).

I would suggest, connect to redirect host even before you accept incomming connections. This way you have an option to reject incommeing connections (or even stop listening if the redirect host is not available)