Hello,
Regarding the issue, you are having in order to run an OpenVPN server inside your office where your RUT240 is getting network connectivity and getting a Private IP address from the office main router. What you need to do is ask your IT guy if your office network is having a Public IP address available then if yes you need to ask him to do port-forwarding to the RUT240 Private IP address assigned by the main router of your office network the default port of OpenVPN is 1194 so if you want to stick with that it should work.
Regards,
Mellow