Sony’s maintenance page has revealed that the PlayStation Network will be undergoing scheduled maintenance on Monday, 23rd March 2015, for approximately 2.5 hours in the evening. The maintenance will begin at 16:00 GMT and last until 18:30 GMT.
For the duration of the maintenance you will be unable to login to Account Management and PlayStation Store.
PlayStation 4 users will be able to access online gameplay only if their system is activated as their Primary system and they have recently signed into their SEN account and have their authentication details cached.
PlayStation 3 and PlayStation Vita users may experience limited PSN functionality, however online gameplay will be available to users who have recently signed into their SEN account and have their authentication details cached.