Well, I dont know how familiar you are with routers or with home networks - that makes it a little hard to advice without starting with the basics. You say you have opened up your ports 80-5000,........... are you sure that you have forwarded them to the correct ip address?
When you plug your PS into your router, does it get assigned the correct, or a valid ip address?
I have to express my displeasure with the false description of a gateway, both in this forum, and in the market lately. A gateway doesnt have to have anything to do with a router or a modem, but can. Today, a router with a built in switch (sometimes called a 4 port router) is also called a gateway by many companies. You cannot go out and buy a "gateway" as some thing. That would be like buying "blue". I cna buy a product hwich is blue, just as I can buy a product which acts as a gateway.
If it helps think about this sentance: there is a gateway which connects one network to another network. In my house, I have a home network. Outside my house, there is an internet network. My router connects my network to the internet and thus is a gateway. Thompson your router should be fine if it is setup correctly, as a real router looks like any other internet signal comming into the device and your Ps shouldnt know the difference except that ther eis a ahreware firewall between itself and your internet.