Installing the Network Adapter
If you have a PS2 model SCPH-300xx through SCPH-500xx, the network adapter is not built-in, and as such, must be installed. To install the network adapter, first insert the Online Start-up Disc or any online capable PS2 game. Using the on-screen keyboard and your controller, you will need to enter your settings. First, you will select a connection speed by highlighting the appropriate response and pressing the "X" button. Next, select automatic setup, as this tends to provide fewer issues when setting up your network adapter. Finally, if your ISP requires a password and user name to log on, it will be entered now, followed by a connection test. If the connection test is successful, press the "X" button to complete the installation and save the settings to your memory card.
Acquiring Your Network Access Code
To get connected to the PS2's network, you need to use your Network Access Code. Online capable games will ask for your Network Access Code during the automated setup process found in online compatible games. The Network Access Code can be found in the back of the console's registration booklet if the network adapter is built in to your PS2, or in the manual for the network adapter if it was obtained separately from the console. If you no longer have the Network Access Code, it can also be obtained by calling Sony Customer Support at 1-800-345-7669.
Memory Card
Many PS2 users are unaware of the actual requirements for online gaming. While most users have a memory card, they don't always have enough free space on the memory card to hold the settings for the network adapter. At least 127kb need to be available on a memory card to utilize the network adapter. If you don't have enough available space, either delete some of your saved game data or use another memory card.
Proper Connections
One of the most common problems associated with using the PS2 network adapter is loose connections. If you have a PS2 model that doesn't have the network adapter built in, check the network adapter itself. Disconnect and reconnect it. Next, disconnect and reconnect the Ethernet cable. Also, disconnect the power from your modem and router (if you have one), wait 30 seconds, and plug them back in. This will reset your modem, router, and Internet connection.
Game Has Been Decommissioned
Over time, Sony has decided to discontinue online support for several games, and as such, they are no longer playable online. The following PS2 games have been decommissioned: WRC 4: The Official Game of the FIA World Rally Championship, WRC: Rally Evolved, Formula One 05, SOCOM: U.S. NAVY SEALs, Twisted Metal:Head-on, Amplitude, Destruction Derby Arenas, Everybody's Golf, EyeToy Chat, F1 '04, Jak X, Lemmings PS2, My Street, Syphon Filter Omega Strain, This is Football 2004, This is Football 2005, and Twisted Metal: Black Online. If you have been attempting to get the online functionality in these games to work, sadly, there is no solution. The titles mentioned can still be played offline, but their online modes are no longer functional.