Disable it by accessing the xmb menu and choosing settings network settings media server connection disable before attempting to connect to psn. Ensure that the ethernet cable is not connected to the playstation 3 system or the playstation 3 system will automatically attempt to connect to the internet via a wired connection.

Ps3 Internet Connection Settings Wireless Connection
Ps3 internet connection settings. Select yes when a confirmation screen is displayed stating that you will be disconnected from the internet. Settings for the access point are typically set using a pc. Make sure that your wireless router is connected to the internet and broadcasting a signal. Choose internet connection enabled. For details contact the person who set up or maintains the access point. The items displayed vary depending on the settings you have selected.
Select internet connection settings. Confirm that an ethernet cable is not connected to the ps3 system. Access the xmb menu and choose settings network settings. The media server connection may interfere with the ps3 systems internet connection. Open your web browser in the address bar type your default gateway as we discussed earlier you will see a prompt for a username and password the default is almost always username. Select settings network settings.
Select internet connection settings. Select settings network settings. Turn on your modem and router. Ensure that all network equipment firmware and drivers are functioning and up to date. Connect a playstation 3 to a wireless network. Scroll down and select internet connection settings.
Turn off all your network equipment modem and router as well as the playstation 3. Look around in your settings for an option called d m z this is a very useful. Adjust each item as necessary for the network environment in use. Leave all equipment off for two full minutes.