Your local network may have caused this error. Please restart your access point (wireless LAN router).
Restart your PS Vita system.
If you cannot connect to PlayStation®Network, check the status of PlayStation®Network at the Sony Computer Entertainment website for your region.
Contact your internet service provider to check the status of your internet connection.
Reset your access point, and then go to the home screen and select [Settings] > [Network] > [Wi-Fi Settings] to connect to the access point again. For details, refer to the access point's instruction manual.
Update the access point firmware to the latest version. For details, refer to the access point's instruction manual.
Go to the home screen and select [Settings] > [Network] > [Internet Connection Test] to check your internet connection status.