Me and my friend set up a server using https://aternos.org (We have it set to forge and 1.12.2 and all the mods are 1.12.2 aswell) I have Forge 14.23.5.2838
All the mods work on single player mode but only a few works on the server
I still get the item menus for Twilight forest, Biomes'o'plenty, harvestcraft and Mo'creatures, but only very few items appear in them and some have nothing at all
I have already built a spawn area so I would be very sad if I had to start over
I'm not very good at stuff like this, so please explain things in detail with steps if you can