So I have been dedicatedly hosting Minecraft servers for me and my buddies for quite a long time now. Well, after years of not playing, I decided to create us a Spigot server to mess around on. Well, this is where the problem arises. After a successful port-forward and server configuration, some of my friends are able to join and some of them aren't. The ones who cannot join get an error message. Strange right? Well, to eliminate the possibility that my personal computer was the anomaly, I moved the server files to my MacBook (using a different run command obviously), and now neither I nor my friends can join. Any help would be appreciated!