This video shows you how to bypass PS3 firmware update 3.21. This allows you to stay on 3.20 and keep any other OS which will be discontinued if you update 3.21
Today, Sony has released a their patch 3.21 which has unfortunately removed the “Other OS” function due to security issues.
Here are the instructions:
1. Go onto the XMB on the start up screen.
2. Go to Network Settings and select Internet Connection Settings.
3. Click Custom – [any option] – [any option] – Manual.
4.For you IP address, you may want to go to your router webpage to find out this remaining info, but for the primary DNS you need to put 22.214.171.124 which should trick the PS3 into thinking you’re fully updated.
5. Choose your settings from here on.