I tried to connect to a LAN world with 12w30a, but the world wouldn't show up under "scanning for LAN worlds" thing. I opened the single player world to LAN and everything i was supposed to do. I think it has something to do with file sharing over my LAN. If you know anything please tell me.
My brother and I are having the same problem, and yes, we are using the same router. We tried to use direct connect, but it wouldn't work. When he first made his single player game, and turned LAN on, it wouldn't show up on my multiplayer screen. However after awhile my single player LAN server AND his showed up on my multiplayers list, but I could not connect to either of them.