Ok, if its NAT type 3, i can help. First, simply try resetting/unplugging your internet. (By the way, what country are you in?) If that doesnt work, reset all your network settings on the PS3, where i beleive you can change the nat type. Also, do me a flavor and go to the tutorial, where You should be playing as parappa. If not, delete and reinstall the beta. Anyway, If resetting doesnt work, I recommend checking your internet manual to see if you can change it a bit.
Hope I helped
I have the exact same problem and came here to see if others had it too. My internet is great and my speed is 30 mbs with a 95% signal strength so don't tell me its a problem on my end because its not. I love the game to death already I just wish it worked more than 10% of the time or so. I usually get into matches with 2 or 3 people (including myself) and then theyre leveling up and and attacking thin air. Then at the end of the match it has a bunch of people who I couldn't see or attack. Another problem I have is getting booted out of matches. I've also run into other players who are grayed out and I can't attack them, but they can attack me (Usually happens after a super). Lastly I've also had to deal with pretty bad teleportation/lag. I love the beta so far and the gameplay itself I just wish it worked better for me. Also, does anybody know how to change the match settings. Like number of players, etc?