Friend can't Seem to Host Server

[Soniku64]

Me and my friends are trying to play a quiet ThreeMan game. My friend has the regular port of 25565 open, yet no matter what we try, neither me or the other friend can connect to his server, we've tried the Vanilla Hexxit Server, and all three of the other options listed on the Hexxit download page (MCPC+, ForgeEssentials, and BukkitForge) with no success. We've also tried changing the port to 7777 (another port we normally use for games) with no success either. The server just doesn't work. Please help!