The default connection to the Sim uses the local host address of 127.0.0.1 through the network stack. The serial port setup shouldn't have anything to do with it, unless the serial settings are causing the Sim to hang...which I guess is a possibility. I'm don't guess the laptop has any serial ports?
Wondering about having to manually enable the link? We normally re-enable the link automatically when you attempt to connect to it, but I have some vague recollection that there might have been a bug in that. We're still about two months away from a new release, but I'm think that might be fixed.