Yes GT4 can't be played online! now quit your doubting and read this link! http://www.teamxlink.co.uk/forum/viewtopic.php?t=8238
has anyone here actually gotten it to work? I picked up GT4 Friday night and spent 2 hours with a dozen guys on xlink trying to connect/host. It just stays at the WFC (waiting for connection) screen forever. I've already read all the threads and crap. dang its frustrating. ! Some of the forums say the straight up LAN mode sometimes doesn't even connect. I spent those 2 hours trying to get xlink to work without even trying single player! [xx(] If anyone has gotten it to work, i'd invite you over to try and set it up at my place. I'll buy beer. on the other hand, xlink is great for Halo1/2 and Rainbow6-3 and avoiding feeding the Micro$oft Live machine. haha
a friend of mine's said he got it to work! i haven't tried yet because i do not have a network adapter for my ps2. picking one up then i will try.
www.gtplanet.net has a whole forum dedicated to getting X-link to work. I haven't tried it yet, but there's a ton of people having success on there. Give it a look. I think it is a sub-forum of the GT4 forum.