Computers within my network get a "Communication error" when trying to connect. I haven't yet had an opportunity to test it on a computer outside my network. I'm using Tekkit 1.1.4 right now, but this same problem occurred when running Bukkit earlier (I forget which version). According to canyouseeme.org, the port is open, so I've forwarded it correctly, which is well and good. But I can't connect to the server within my network. When server-ip= has no value after it, I can access the server using localhost, but not from a different computer in the network. I tried putting my internal IP there, but that just renders localhost unusable, without any access available to other computers. When I add the internal IP to the servers list in minecraft from another computer, I get this message: This happens even when I'm using a computer that supposedly can't access the server. I've looked everywhere for a solution to my problem, but nothing's come up. If anyone here can help me, I'd be much obliged. I'm running Windows 7 64bit using jre6. Bukkit build git-Bukkit-1.0.1-R1-b1597jnks. Plugins listed in the plugin folder are ChopTree, CommandBook, RecipeManager, and WorldEdit. Folders outside of the plugins folder that aren't there in normal bukkit are Buildcraft and Redpower. Any other plugins added by tekkit are also presumably there, but the problem is the same whether using Bukkit or Tekkit. EDIT: It's occurred to me that Tekkit may be different enough that help isn't possible here. If that's the case, please say so, and I'll switch forums. The problem is the same with both programs, but I'd understand if you didn't want to deal with it.