I am not sure in whici way but something has been modified in TCPRecv function because this function worked well but now it makes no sense for me. Server TCPStartup() $Server = TCPListen(@IPAddress1,12100) Do $Socket = TCPAccept($Server) Sleep(10) Until $Socket <> -1 While True Sleep(10) $Recv = TCPRecv($Socket,2048) $Err = @error ConsoleWrite($Recv & @TAB & $Err & @CRLF) Wend TCPShutdown() Client TCPStartup() $Socket = TCPConnect(@IPAddress1,12100) Sleep(5