If you connect to the Internet via a proxy server, turn off the proxy server.
Check the network connection on another wireless device. If other devices are experiencing connectivity issues, there may be a problem with your network. Contact your Internet service provider for more information.
Ensure that all network equipment supports 802.11b or 802.11g wireless protocols.
If your wireless network is protected by a WEP or WPA password, check that this has been entered correctly.
The Media Server connection may interfere with the PS3 system's Internet connection. Disable it by accessing the XMB Menu and choosing Settings > Network Settings > Media Server Connection > Disable before attempting to connect to PSN.
Ensure that all network equipment firmware and drivers are functioning and up to date. Visit the manufacturer's website for instructions on how to update your router settings.