Startup Issue with Minecraft - Starts but cant join. was able to join running vanilla

[ThePotatoKing]

Please provide actual errors, server type, etc.
I would assume Forge, if so, follow this:

Forge Frequently Asked Questions

Forge Frequently Asked Questions How do I run Forge using: start.sh/start.bat? No need! AMP handles all that for you. Just select the version of Forge you’ll need, hit update, and start your server. Where do I put custom start up arguments? You can find this options under: Configuration → Java and Memory → Additional java options I installed a modpack using AMP’s FTB downloader, why did it start in Vanilla? or The update manager reported a successful update, but ./Minecraft/minecraft_server.j…