Placing your PlayStation 3 Console in a De-Militarised Zone (or DMZ). This means that your router will not block any internet traffic to your console, leaving you free to breathe the open air of MW2 multiplayer goodness. Ahhh....
Placing your console in a DMZ is not a difficult thing to do, but you will need to set aside half an hour to get to grips with the process - and you'll need administrator access to your router.
First things first, turn on your console and go to Settings > Network Settings.
From here, you can change all the bits and gubbins which help your PS3 connect to the internet.
You will need to give your PS3 a static IP address. IP addresses are like street addresses, only for your internet network. A static IP address will ensure that your router always knows where it can find your PS3.
To do this, first you'll need to go to the Settings and Connection Status List and make a note of 2 numbers:
1. The 'IP Address'
2. The 'Default Router'
Once you've got these, back out of this menu and go to the Internet Connection Settings menu. From here, follow these steps:
1. Select 'Custom'
2. Select the type of connection your using (If your PS3 is plugged in to the router, select 'Wired', if not you're using a wireless connection, select that intead.)
3. If you selected wireless, set up your connection as normal untill you get to the IP Address menu.
4. If you selected wired, select 'Auto-Detect' at the next screen and continue to the IP Address menu.
5. At the IP Address menu, select 'Manual'.
Remember those numbers you marked down earlier? Here's why you noted them!
You'll now see a screen with 5 options:
Here, you need to input the number you noted down earlier. However, you should change the last group of 3 digits to something else. Your safest bet is to increase this number by 50 and use that. So, if the IP address you noted earlier was 192.168.0.50 then your new IP address would be 192.168.0.100
Note that the numbers here only go up to 255, so use that as a maximum if you need to. Be sure to ONLY change the last group of numbers! Make a note of the number you decided to go with.
This is almost always 255.255.255.0, don't change this unless you have a specific reason to do so.
The second of the numbers you wrote down, all you need to do here is input the IP address of your router.
This bit is super easy. Remember the number you placed in 'Default Router'? Whack it in here again!
You don't need anything at all here, unless you have a specific reason to input a Secondary DNS.
Once you're done here, make sure to make a note of the IP address you entered at this menu and hit right on the d-pad to advance.
6. For MTU - select Automatic
7. Do not use a proxy server, unless you have a specific reason to use one!
8. UPnP - it's usually a good idea to enable this, but if you have voice comms trouble after using this guide, try disabling it.
9. Review the settings and test the connection!
Now, don't panic. Your PS3 may scream at you that it cant connect to PSN. In the words of Revolver Ocelot, "We're not finished yet!"
Your next task is to log on to your router as an administrator. Check your router's manual for details on how to do this (alternatively, google is your friend).
Somewhere in the plethora of settings and techy bits that make up your router's menu will be an option to assign a 'DMZ'. I cant point you directly to this since every router differs, your best bet is that good ole' friend google.
Once you find it, you'll be asked to input an IP address for your DMZ. Here, you need to put in the IP address you gave your PS3 earlier, the one you noted down after step 5 of this guide. Once you've done that, save your settings, wait for your router to sort itself out, then dance a bit - you're nearly done.
Troop over to your PS3 and go back into Network Settings. From here, select Internet Connection Test. If all has gone swimmingly, your test will be successful and your NAT Type will read '2'. Hurrah! Your console is demilitarised and has nothing to fear from aerial bombings* or multiplayer connection troubles.