The online racing portion of LBPK is still not working properly... Everyone keeps getting kicked!
UFG please fix this!!
It's not fun if you can't race with your friends.
2 months is long enough...
The LittleBigPlanet series (LBP1, 2, Karting and even Vita) is extremely *extremely* picky about internet connections and setups. For now my suggestion is to manually forward all ports and make sure you have as much bandwidth as possible going to your PS3.
The network demand of LBP is much more demanding than most games even with only two players.