FVS336g V1 -UDP PORT 500

I am trying to forward UDP from the Internet to the internal network. So I take it that I am unable to pick and choose which ports I want to use in this case forward to my internal network?

FWIW having spend 40+ mins on hold with Netgear support, this is now described as a known Bug with the current firmware - for some reason several standard ports are now missing from the default service ports and surprise I can't add this UDP port as a custom service port. No current ETA on updated or beta or new Firmware. Prior version of firmware also has this "bug". It was also interesting to me that the 2nd level tech support for the FVS336G is NOT using the latest avail firmware - that sure makes it interesting for current paid customers with support contracts to get support, I am now sitting with a unit with a support contract that has 2 yrs to go and no support available for a known bug for the last two firmware versions...... Its Time for Netgear to pick up and fix these known bugs or face losing customers with paid support contracts - I am very disappointed.