On my ps3 i my NAT is set to 3 but i need it to be at 2 how can i fix this?

The first thing you will want to do is check your network connection. Head on over to the Network Settings tab on the XMB.
You will receive a warning letting you know that you will be signed out in order to perform the test. 
You have Type 3, read on for help on opening up your NAT in order to open up your NAT on your PS3 you will need to make an adjustment on your PS3 and on your router. First you will want to set up your PS3 for a static IP address. This means turning off DHCP and assigning your PS3 a single, static IP address. Before you start this process head over to the network tab on the XMB and choose "Internet Connection Status." From here note your current IP address, your subnet mask, your default router and primary and secondary DNS settings. Write these down, you will need them in the following steps.
To do this, visit the Internet Connection Settings tab on the XMB.
From here most of the settings can simply be passed through with default settings. There are two areas, however, that you have to change. The first is choosing a Custom address setting (instead of Easy)from here, you will want to choose Manual IP Address Setting.
Remember the settings you wrote down from your status page? You will need them here. You will have to enter in the static IP Address you want to assign to your PS3, the Subnet Mask (which is usually 255.255.255.0), the default router (the IP address of your router, most often 192.168.1.1 or 192.168.100.1), and the Primary and Secondary DNS settings. You will have to input all of these numbers. This is made much easier with a DVD Remote or keyboard.
You will want to set the last number of your IP address high enough that other wireless or wired items on your network will not be assigned the same number through DHCP. While DHCP had chosen .3 as an IP address for my PS3 initially, I bumped it up to .23 because I have less than 23 items in my network. If you do not have DHCP enabled on your router, you do not need to worry about this and can simply choose an IP address that does not conflict with your other devices and which is available through your router.
Once you have all of the settings input, press X to save them. Your settings will change and the PS3 will offer to perform an Internet Connection Test for you. If you let it do the test now chances are you will still get a Type 3 NAT connection. Don't fret little bear, we still have one more step.
In addition to making the necessary changes on your PS3, you will also have to open up some ports on your router.
Once you have forwarded these ports and saved your settings its a good idea to unplug and plug back in your router. This will refresh everything on your network connected to your router. Once done head back to your PS3 and perform an Internet Connection Test.