Minecraft FTB LAN Problem?

So my brother and I would like to play on an LAN server together. We're in the same house, connected to the same wifi. Though I've no idea if it makes any difference, he's using a mac and I'm using a desktop Windows 8 comp. We're both trying to play the Agrarian Skies modpack together, though when we go in (either of us) and press open to LAN, neither of us can see the server when we go into multiplayer. I've struggled with port forwarding to this point until I gave up and tried to use Hamachi. Both got into a network, fixed the server launcher and started it up again. This time when I inserted my IP into the multiplayer add server list, it showed up and said 0/20 people on the server, as it should have. When I gave my brother the IP, it didn't connect at all. So is there any way to fix this at all? I tried giving him multiple IPs as well, but none of them worked. Can I still do this over LAN? Do I have to screw around with port forwarding some more?

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