This network mostly consists of Modded Forge servers, IE, minecraft servers that use the Forge core and API to add mods (unique from plugins) to the game. Unlike more “vanilla” servers with plugins, most mods must be also installed on the client, the client has to run a modded instance of the game with forge, and mods almost always must update per minecraft version to work. Another method to do mods is with Fabric, however, I (ghost_s1) do not have much experience with Fabric packs, let alone servers.