I have created a custom nether world using WorldPainter, and I want it to be used on my server. However whenever I put the world onto the server, and name it "world_nether", I go onto the server (I do that all while it is offline of course) once it's back up and then I go to the nether and it's the default nether. I'm very confused and I can't find anyone online having the same/similar issue.
Are you naming the folders properly? spigot uses different region folder names than vanilla, if the folder is world-nether/DIM-1, it needs to be changed to world-nether/region
They are not "world-nether". They are "world_nether". I am using the folder exported by WorldPainter. I did not edit anything in them.
You need to take the files from the world_nether folder and put them in the default vanilla nether folder.
level.dat and other dat files go in server\world_nether The .mca files need to go in server\world_nether\DIM-1\region
Just tried copying all of the mca files in the world_nether world I made into the world/DIM-1/region/ directory, but it doesn't seem to work still. Same result, it generates a whole new nether world instead of using my pre-created one.
How large was the world you created with world painter? Normally the area outside of your created world will be generated by the server. Are you sure you are in the right area that you created when entering the Nether?
When you created your nether. Did you start out with a default map and use Edit/Dimensions/Add Nether or did you just start with a new world and changed it to Netherlike?