Thanks to a group called Lizard Squad the PlayStation network is still down.
Sony said today that PS4 owners who are unable to connect could fix the issue by changing their MTU settings.
A tweet by Sony said this might be unnecessary due to a fix on their end.
However, if you’re having problems you may as well give the MTU fix a shot. It’s pretty straight forward.
1. Navigate to [Settings] > [Network].
2. Choose [Set Up Internet Connection].
3. Now choose either [Use Wi-Fi] or [Use LAN Cable]
4. Choose [Custom] on the next screen.
5. Select your normal settings for IP Address Settings. (Note: If you do not know this setting use [Automatic].
6. Select your normal settings for DHCP Host Name. (Note: If you do not know this setting use [Do Not Specify].
7. Select your normal settings for DNS Settings. (Note: If you do not know this setting use [Automatic].
8. Select [Manual] for MTU Settings.
9. Press enter to pull up the keypad and enter a new value and press X.
• First use the MTU value of 1473.
• If the connection test is unsuccessful, try the MTU value of 1450.
10. Select [Next] to continue.
11. Select your normal settings for Proxy Server. (Note: If you do not know this setting use [Do Not Use].
12. Next – [Test Internet Connection]
13. You will see a value under (PSN Sign-In – Successful) if this process was successful.
Hope this helps.
Let us know if this fixed the problem in the comment section below!