Dropping a plugin into a Forge server does nothing. Dropping a mod into a Paper server does nothing. They are not two flavours of the same thing — they attach to the game in completely different places.
What you are seeing
- A jar sits in the folder and never appears in
pluginsor the mod list. - The console never mentions it, not even to complain.
- It works on someone else's server but not on yours.
Why it happens
Plugins use the Bukkit API, which Paper and Spigot provide on top of the vanilla server. Mods use Forge or Fabric, which patch the game's own code. A Paper server has no mod loader and a Forge server has no Bukkit API, so each simply cannot see the other's files.
What to do
- Check which folder the jar is in
Plugins go in
plugins. Mods go inmods. If your server has only one of those folders, that tells you which kind it accepts. - Check the download page before installing
SpigotMC and Bukkit host plugins. CurseForge and Modrinth host mostly mods, though Modrinth also lists plugins — read which one the page says.
- If you need both, look at a hybrid — carefully
Projects like Mohist and Arclight attempt to run both. They work, up to a point, and they are known for subtle breakage that neither the plugin nor the mod author will support.
The jar loads and the console names it at startup. Silence means it is in the wrong kind of server.
Most things people want plugins for on a modded server — permissions, claims, homes — have mod equivalents. Searching for the feature rather than for the specific plugin usually finds one.