Connecting to Unity Pro PLC Simulator

'm having troubling connecting to a Unity Pro Simulator with PC .(do i need plc to make it work)

I'm using the loopback address (127.0.0.1) for the PLC. dosent connect. im getting this massage.

Any suggestions or tips would be greatly appreciated.

you dont need a plc no, i'd guess its a firewall or antivirus giving you grief.

Have you selected simulation mode in the build menu