See the in-game manual > port forwarding
Ok, not sure if this will solve your problem
Simply, exit all the way back to the main screen where you can choose GT Mode, wait for it until you see the "updates" section loaded, head back into the game are you should be reconnected. Then try to join an online game and see if it works.
I have the same problem too. It's either I can't join a lounge or I can but after one minute I'm disconnected from the server. I'm searching for a solution for almost a month but I can't find one. I have to say I had the same problem with GT5 prologue.
Ohh, I think I had this problem all the time. Now I'm just waiting for WRS to start. Still hope to get it fixed though.I actually don't think I had this Problem before the update I will try to Join a Friend's Lounge (which is the only way I played online before the Update)and see if it still works .I still can create and Join my own Lounge .Hope somebody fixes this I want to play online really bad 👎
Try refreshing system cache, it's in the options then go to network settings.