Hey! Aeternum is tested and confirmed to be working on multiplayer. Make sure you both have unloaded and reloaded the mod in the launcher to make sure it is fully enabled. Sometimes, when you first download a mod, is says it is loaded in the launcher when in reality is isn’t. The above solution fixes that. If not, i’m not sure what the issue is as everything is fine on my end and for other players. Hope you can get it sorted :)

ty it's working now :D