I just got a smooth stepper working this week so I'm not an expert. My Smooth STepper connects through the Ethernet port. On my computer the Ethernet plug is a little loose on the computers Ethernet port. Wiggle the cable just a little bit and the Smooth Stepper shuts down due to lack of communication. In actual use I'll need to tie down the Ethernet cable to eliminate the wiggle.
Just think, the old parallel port was a nice snug connection with 2 mounting screws.
Just a thought,
Jim