So i was playing with my friends and we decided to do the forge server setup, we installed mods in both directories (.minecraft mods and server mods) and started playing, everything seemed fine, but then we thought "why not add a crafting related mod" so we dowloaded the furniture mod and restarted minecraft, but we cant make furniture with the right blueprints? we tried everything, and then i decided to go creative and try to spawn one, it appeared instantly, then dissapeared in a milisecond, it was still on my inventory but i could never spawn stuff, nor galacticraft rockets, not furniture, not equip a backpack from a backpack mod, i tried everything, and im really desesperate, any help please? (PS: english aint my main language)
EDIT 1: here are some screenshots of the folders, cuz maybe i have an incompatible mod or something:
https://gyazo.com/a3290eabca3a81a9ea68f12845c941b0
https://gyazo.com/59b95abead664193ee9039a909e562a6
https://gyazo.com/3d2cfae506c486e86ca1e7f40348b9f2
https://gyazo.com/44e04f79268fd9bfa747bf04a740ebfa
(on .minecraft i have optifine installed, but not on the server, just saying)
EDIT 2: Im also using 1.12.2
EDIT 3: After looking some information up, i have found why this happens, but i have no clue how to fix it, apparently my server is vanilla, i saw 1 person that simply deleted everything from the server's folder and reinstalled it and it worked, but for me, it doesnt work, any help on how to remove vanilla? i need an urgent reply, please.