The second scheduled PlayStation Network maintenance this month will take place later today from 10pm PT until 11pm PT.
PlayStation 4 is listed as the only affected platform, and Sony continues to recommend that you activate your PS4 as your primary console “so you can continue to play most games and use 3rd party services during maintenance.” You can do this by going to [Settings] > [PlayStation Network/Account Management] > [Activate as Your Primary PS4] > [Activate].
Here’s their message about this PSN maintenance:
Anyone who already has an account can still sign in to their PlayStation Network profile, play games, and use most applications while this maintenance is carried out. You will not be able to access PlayStation Store and Account Management during this maintenance. We apologize for any inconvenience.
According to Sony, they’ll be performing the usual “routine maintenance and improvements” during the downtime.