I Think I Found a Bug with Port Forwarding on AC66U

You cannot use the same port twice even if you assign it to another IP? That makes no sense unless I can assign more than 1 IP somehow to that same port? For Example my XBOX and Net Extender both need Port 53 open. I can only enter that for one or the other even though both devices have different IP addresses.

I know I was able to do this on my Buffalo Router with DD-WRT.

Any suggestions on a workaround? I am on the Firmware version 1 below the latest version. I had a problem...

I Think I Found a Bug with Port Forwarding on AC66U