This thread is old, but still a sticky so I think I will just add to it.
When trying to correct an error I was getting from call of duty, I wanted to make my NAT type open and not moderate (I'm not sure why it was moderate in the first place). Upon doing so I sped up my connection and things work better then ever now. If you wish you can add the following information to the OP, if not that's okay too. I hope this helps someone out there
It's easy, and takes 5 minutes so give it a chance.
The first thing that can be done is to create a static IP address for the router your PS3 connects to.
The second thing that can be done, and should be done, is changing the DNS your PS3 connects to. This step is the easiest and takes the shortest amount of time.
Okay, lets start with the static IP address. So what is a "Static IP" anyway? Well, I am sure you are aware that all computers have IP addresses. The IP address is essentially the "Phone Number" of your computer. No, you can't call it, but you get what I mean. Every time you turn on your computer your IP address changes. We want to make it so the IP address does not change, no matter how many times we turn it on/off. I shall break how to do this into a list form, so follow closely. Any questions/comments, feel free to make.
-First off, check to see if you already have a Static IP address. Go into the Control Panel from the Windows START menu, go to networks and connections, and depending on what windows you have depends on how you get to your network connection properties. For me, I had Vista on the main computer and had to go into "manage networks" in the left column. Right click the network connection that your PS3 uses and select "Properties." Then select the thing that has "TCP/IP" in the brackets next to it. Then click the properties button. If the "Obtain IP Address Automatically" option is selected, then you do NOT have a static IP address and should read on.
-So you don't have a static IP? Bummer. Don't worry, we will get you there. Again, this has to be done on the main computer of the network. I.E. if your router is connected to a computer and also has a wireless connection to a router in a different room, you cannot use the computer in the different room to do this. Smaller steps now, so you will not be intimidated.
-Open Windows START menu and search "run" without the quotations.
-Type in the prompt "Command" (again no quotations)
-You will get an awesome screen of nothing but black and some white text. Type in "ipconfig /all" and hit enter(without the quotations and make sure the space between config and / is there)
-HOLY CRAP! A bunch of numbers just started flooding the black space, right? Well grab a pen(cil) and paper because you are going to manually write 5 of these down!
-Look for the IP Address number (something like 192.168.1.1), Subnet, Default Gateway, and BOTH DSN Numbers. The DSN numbers should look almost identical except for maybe one number. Write all of those down. Double check them as well.
-Go back to the very first thing we did, which was when you checked and saw you didn't have a static IP address. Follow those instructions again.
-When you see "Automatically obtain IP address" option clicked, click the one under it. You will now have to manually enter in all those numbers you wrote down EXCEPT THE IP ADDRESS. The IP ADDRESS should be different, so add or subtract a zero (I.E if it was 192.168.1.1 make it 192.168.1.10)
-Save, and then see if you can access the internet and other web pages (like google). If you can, congratulations, you are done! If not, go back and double check everything you did and all the numbers you wrote down. You can also change it back to automatically obtain if you wish.
The easier one! Either you have a static IP address, had one and still do, or you are not making one. Either way, this next step is pretty simple. We, again, will do this in steps.
-Get on your PS3 and go to the network settings section (under, strangely, settings).
-Go to "Internet Connection Settings"
-Continue, which will log you out, and select "Custom" at this screen.
-Picked wireless/wired, select scan (or manually enter it if you know it/it is already there)
-Select your security, then for IP Address settings select automatic, then on the next screen "Do Not Set"
-Here is the important section. Select "Manual" for DSN Settings. You will see a Primary and Secondary DNS number. First go to primary and hit "X". From left to right, the numbers are (separated by the dots) 22.214.171.124. Next go to Secondary and enter in 126.96.36.199.
-An alternative set, if the above does not work, is 188.8.131.52 (primary) and 184.108.40.206 (Secondary)
-Automatic, Do Not use, UPnP Enable (seriously, don't disable this)
-Save, and test connection. If you get passed the "internet connection" portion, then you are good (it is the second one down under "obtain IP address").
-The end, enjoy your games