Suggestion 1: PSN may be offline. You can check the status of the PSN here.
Suggestion 2: If PSN is online and you receive this error, your IP address has been blocked for activity that violates the PlayStation™Network Terms of Service and User Agreement. The activity may have been caused by one or more devices connected to your home network that may be infected by a computer virus.
We suggest that you perform a virus scan on your devices, which may restore your access. Consequently performing a virus scan on all your network connected devices could potentially be effective to improve the situation. If you need further information, contact your ISP. Your ISP has been provided with detailed information, please contact them for further investigation. Once the matter has been resolved, your system will be automatically unblocked.