As you'll know if you've got FIFA 12, it now gives you a 'Firewall Status' on the main menu, and it'll either be 'Open', 'Moderate' or 'Restrictive'.
If it's 'Open' - Then you should be fine, and have very little problems.
If it's 'Moderate' - You may lose connection every so often, and have more lag then the people with an 'Open' status.
If it's 'Restrictive' - You'll be playing the game and I'd guess it'll be laggy, hard to find games? And you'll lose connection pretty often (doesn't happen with everyone)
Well, I had this problem and I was on 'Restrictive' and after searching the Internet I found a nice guide which helped me get my status to 'Moderate' and depending on the type of the, it'll be 'Open', normally how this works is: If you're on 'Restrictive' it should get you on 'Moderate' and if you're on 'Moderate' it'll get you on 'Open', or you could even jump from 'Restrictive' too 'Open'.
Anyway, here is what to do.
First of all we need to access your router.
Open your web browser.
Type 192.168.0.1 into your address bar. (sometimes can be different dependant on your router brand/model)
A popup will appear asking for a username and password. By default:
Password: password/1234/admin or hopefully it has been changed by whoever setup the network.
You should now be logged in to your router.
Now we need to go about enabling UPnP and DMZ.
Look for an advanced or gaming tab or something along those lines, again depends on router brand.
Look for UPnP first as this usually only requires a box being checked to enable it.
Enable and save once you got this done, gets it out the way.
Now look for DMZ, it can be under firewall or security.
Once you find it, enable it. Again usually requires a box being checked.
When you enable it, you need to set an IP for it. This will be the IP of the 360/PS3 that you'll set on the console later.
IP: 192.168.0.200 (bold part is the key as this is what makes it unique for your device)
Should now be done with the router settings, save and reboot. Usually reboots automatically when you change settings.
Consider doing a hard reboot just to be sure. Do this by unplugging your router and waiting 30 seconds before plugging it back in.
Finally we are onto the console itself, start up your machine and go to Network settings.
Here you need to set your IP manually. Change "automatic" to "manual",
When you change to manual you will now be able to set a static IP. This will be 192.168.0.200. (remember this is what you set earlier)
Save the settings and test the connection, should now test with no problem at all.
Load up FIFA, go to the online section and see if it now says: Open
This should now be you up and running for an improved online experience.
If you do this, and have any problems, just post and I, or someone else will try help you.
And this IS perfectly save, EA even suggest doing it.