We only have documentation for communication with PLCs using the GX series software. I’m not familiar with the FR-Configurator2 software. Does Mitsubishi have instructions for using the software to connect to a device over a VPN? The eCatcher software is a pretty standard OpenVPN client, so if you can find those instructions, they should work with eCatcher.
Also, take a look at section 7.2 of our Mitsubishi PLC App Note and see if those instructions look similar to the software you are using. You may need to explicitly add the IP address of the VFD because broadcast traffic is not forwarded to other networks. (Although you can enable broadcast forwarding in the Ewon).
Let me know if you have any questions.