Not heard of a 626 error before, but all other 62* errors relate to your network connection.
Double-check your connection & port-forwarding if required.
Also, use a game's built-in network set-up functions rather than the Network Access Disc, to configure your settings.
If you still cant get it to work & are using a router, try setting up & connecting directly from modem to PS2. If you can connect successfully that way, then its got to be something to do with the connection when you use the router.
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