My 8200n has a section called Virtual Server, with a Port Mapping sub-section. I simply chose a pre-defined application from the list to allow HTTPS forwarding to an internal IP. I also put my rules in the Firewall section, although I guess it might work without anything in there - if I wasn't so lazy I'd test it
As I suspected it's the same on mine, I've removed all the firewall rules and left the virtual server stuff in there. I know it's not a man-thing to do but I really ought to read the manual to see why that makes a difference