Internet Connection Issues
Determine that your Internet connection is working properly if you have issues with your Internet connection. First check that your Internet hardware is connected, including your modem and router, with the cables firmly seated. If your PS3 is connected via Ethernet cable, ensure that the cable is connected as well. You may also need to reboot your modem and router. Test your Internet connection on the PS3 by going to "Setting" > "Network Settings" > "Internet Connection Test." If you need to change your Internet settings -- such as after changing your connections SSID or password -- go to "Settings" > "Network Settings" > "Internet Connection Settings."
Login Credentials
Ensure that your username and password for the PlayStation Network are filled in correctly. You can manage your sign in credentials by going to "PlayStation Network" > "Sign In." If the network is hanging on the sign-in, this option will show as "Signing In..." If you need to change your password by selecting the "Forgot Your Password?" option on the sign-in page, you'll need your username and birthdate to reset the password.
Opened Ports
You may need to open certain ports on your wireless router to get the best connection possible on the PlayStation Network. The procedure for opening ports varies depending on your router; the website PortForward.com offers tutorials on opening ports for dozens of different router models, organized by manufacturer. The PlayStation Network uses TCP ports 80, 443 and 5223, and UDP ports 3478, 3479, though if you use voice chat over the PlayStation Network, you'll also want to open port 3658.
Network Errors
In some cases, the PlayStation Network may just be down. In early 2011, the PlayStation Network encountered some errors and left users unable to connect until mid-May. If your network is properly connected and all the hardware is in good working condition, your login credentials are correct, and your software is working correctly, the issue may be with the PlayStation Network.