Added TcpServer inheriting  QTcpServer - construction of QTcpSocket from nextPendingConnection needed slight modification for the sake of mulithreading. I found KEEP_ALIVE option in Qt - I did incorporate it, but from what I read It could take a lot of time to detect if given socket is dead - on linux its circa 2h...
Server accepts new connections and handles correctly closing connections - if closed gracefully.