Since version 0.9.6.0 there are timeouts canceling the connection functions if they use too much time. When using serial connections the time to send and receive data is much longer than TCP/IP connection times. As the result serial connections are not usable in versions since 0.9.6.0. The timeouts will be increased for serial connections in the next version (after 0.9.6.2).

Hint: Increasing the timeouts is not critical, because timeouts does not do enything more than pressing the Cancel button in the send and recieve dialogs.