A bunch of mods make my friend's game crash, but not my server and not my game

[imtheluk]

Hello everybody! Uh actually I have some problems with a modpack I made myself. This isn't my first one at all, and all the modpacks that I've ever done worked, if we put apart easily-fixed compatibility issues.

So, I'll write down the list of the mods I am using (including the APIs) just later. As I said, my game works normally, my server works normally with the exact same mods and the exact same Forge version (oh yeah, bc we're on forge 1.16.5-36.2.0)

Here are the mods :

abnormals_core AE2 Architectury Ars Nouveau Astral Sorcery AutoRegLib Better Animals+ citadel0 CodeChickenLib Cofh_core Create Flywheel Curios Endergetic FTB Library and FTB Ultimine GeckoLib HWYLA Ice And Fire Immersive Engineering InsaneLib JEI (of course) Journeymap Mantle Mekanism (+ Generators and Tools) Nature's Compass ObserverLib Optifine (yeah I swear) Patchouli ProgressiveBosses Quark Refined Storage Serene Seasons Small Ships (his idea..) Tinkers Construct Thermal Expansion/Foundation/Innovation Corail's Tombstone Twilight Forest Valhelsia Structures (and Core) Waystones Carry On Iron Chest (useless, but he wants pretty chests)

I want to add that there are NO crash report when his game crashes. Like, the game loads and fully constructs the mods and just before arriving on the title screen of Minecraft, his game crashes. Moreover, the error code is 0. He has 18Gb of RAM and he's giving 10Gb to Minecraft. I am playing with 10Gb without any problem.

Also, I already tried installing only a mod by a mod, but when it comes to ~17 mods, I can't add one more mod, like, with any mod I want to add, it crashes. Even if I add a little mod as cofh_core or Iron Chest.

 

I know this post is reaaaaally long, but it could be really great if you guys can help me.

[imtheluk]

I'll send it in a few hours, he's gone to sleep.