Hi Jon,
Seems like you got no problem with setup for GUI.
This error suggests ((ENTRY : >GUI_ERR_LB_MSG_SERVER< >0128< >Logon balancing error %d: Cannot connect to message server (rc=%d)\nDo you want to see detailed error information?<)) your port configuration is wrong.Please ensure you are trying to connect to a valid IP destinations.If your are using a VPN connection ensure it is connected to network before working on it.A basis folk can help you in this.
Hope it will address your query.
Regards,
Kannan