BungeeCord x SpongeForge x PureForge

I want to setup a network such that

BungeeCord

  • SpongeForge lobby (Latest Sponge stable build)
  • PureForge modded server ( Forge 1.12.2-2601)

However I cant send players from lobby to the modded server. Is there any nice guide around?

BungeeCord ------>bukkit or spigot (lobby)--------->forge(mod)