So I deleted "DIM-1" in "world-nether" so I could regenerate my server when I restarted my server.
After restarting I noticed my console never said anything about generating the nether again, so I tried going through the portal so I sat there and nothing happened. When I checked the nether folder again DIM-1 still wasn't there, anyone know a fix?
I am upgrading the server from 1.15.2
Looks like a modded (e.g. bukkit) server structure. Contact the developers