This indicates that the PortServer is not setup properly to use for realport. By default the PortServer is set to set port dev=term this means that DDR-RTS are high and the PortServer sends a login. This must be changed for realport to a passive setting which will not generate a PortServer login:

set port dev=prn auto=off range=(port_numbers)

The unit should be rebooted for this change to take affect:

boot action=reset

This will prevent the PortServer from generating a login. The port will be in a neutral state for realport to control.