Why can't I connect to a Minecraft LAN server?

I think it may be my new computer, but I don't know. I remember thinking about this a while ago when I hosted a LAN server for me and my cousin, and he couldn't connect. More recently, my brother hosted a LAN server, and while my sister could connect, I had to go through the direct connect to finally play. I can play online servers without any problems, it's just LAN that won't work without direct connect.

What's really weird is that I have no problem joining and hosting Terraria LAN servers. It's just Minecraft that has so far given me this issue. I've tried turning my firewalls off, but that didn't seem to help as I still could not connect.

By the way, this is all in Minecraft 1.7.2. Don't know if that means anything, but that's that.

Any suggestions?

If you're hosting the server on your computer and you want to connect to it, connect by entering 'localhost' (without quotes) into the IP address box. If someone else is hosting in your household and you want to connect to their server, connect via their ipv4 address. To find their ipv4 address, on their computer, open command promp, type 'ipconfig' and look for the ipv4 address. An example of an ipv4 address would be 192.168.0.4, 10.0.0.4, etc. Also, make sure both of you are connected to the same network. You may even want to consider making your own private network, as I've heard that sometimes certain networks can interfere with LAN play and make it not work.

Good luck, and feel free to contact me through my profile if you're still having issues.