Hello,
In the WebUI of the router, could you navigate to Network → Firewall → General Settings and make sure that Forwarding is enabled on all OpenVPN zones?
Also, are you using the command described previously (ping 192.168.1.22 -S 192.168.255.xxx) to ping the PLC from the OpenVPN client?
As I understand, you are now able to ping the VPN tunnel IP of the RUT240, correct?
Best regards,
DaumantasG