Hmm, I had the same thing, my nat type was always moderate and no matter what forcehost wouldn't work for me because you need a Open NAT Type. Here do what I did: Run Command Prompt as administrator, so right click on it and click "Run as Administrator"
then type the following and click enter after it: ipconfig/all It should display a bunch of stuff, scroll up a bit and find Wireless LAN Adapter Wireless Network Connection:
Then under it should be IPv4 Address: and it should show you your computer address. Here's how mine looks like:
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Now that you have that, go into your routers connection, I get to mine by simply going to 192.168.0.1. But yours might be different.
Then the IP that you saw in the command prompt beside "IPv4 Address:"
DMZ it. That should work, now restart your PS3 and go on Ghosts