Router's are funny things- you set them up just so and sometimes they still don't do what you want.
Having the PS3's IP address should mean you don't have to bother with ports. I will assume you did remember to click the "enable" button when you set this up.
Sometimes the simplest solutions work best- at times a router may need to be power cycled to get things to take properly. I would suggest doing this and see if things improve.