Cannot connect to debugger (could not locate target IDE)

Lately, using Xojo 2017.R3 and debugger Desktop 2.3 on remote virtual Macs using parallels,
I’ve been getting the above error, after the debug app tries to launch.
The full error is: “Cannot connect to the debugger Since we could not locate the target IDE to start a debug session, this application will now exit.”
Rebooting both Macs does not help.
Does anyone know how to fix this?

Check the networking on both VMs, make sure they can “see” each other… Make sure the debugging port is open… Hopefully you get a better answer when everyone wakes up…

Like Shao said, I had my firewall blocking it. oddly it could create the file and transfer it, but not connect to it.
Changing the firewall settings solved it