Port Forwarding issues (I know most generic thing ever) [java] 1.12.5

I a little bit ago I bought myself a 1SU dell server so I could run well multiplayers server on it. I have tired on mutliple devices to port anything from my server with no luck. I can join the game since I am the local host but anyone outside my network cant, I am really at a loss here trying different routers different softwares different tools different ports different firewalls and 100 other things. Any help is really apreciated.