For those of you having trouble with hosting in MGS PO and PO+, this will fix that problem
HOW TO FIND YOUR SETTINGS IP
1. go to start and hit run
2. type in cmd
3. once in command prompt type ipconfig/all, hit enter
4. a lot of ip info will pop up now, find the ip by default gateway and type that IP into your URL bar
THIS SETTING IP IS FOR LINKSYS ROUTERS, I'm not a network expert but if you don't have a linksys router check online for your settings IP
1. copy and paste this in your URL bar
http://192.168.1.1 
2. it will take you to your router settings, click on the tab called Applications/Gaming
3. then you will see under it 2 options Post Range Forward and DMZ, click on DMZ
4. You will see 2 option bubbles, select enable
5. under the option bubbles you will see DMZ Host Ip Address, the last part of the IP you can edit

6. Hop on your psp and head to network options, select test connection, when its finished check your IP fill in the last digits of your IP in the DMZ Host IP Address box

7. You're done now you can host games
If you are prompter for a password try these combinations
username:admin
password: (no password hit enter after entering in admin in username)
username: admin
password: admin
(these are the defaults passwords for linksys and if you haven't set any passwords on your router should work)
I'll post some screenshots later