Network Problem/No Replication

Hayhoo -(°-c° ~)
So my problem is that a lot of things do not replicate. For example my Player projectile does not appear on the other instance, my players rotation only works for the server and anotherexample would be that my destructible Meshes seem to act like every Clients personal destructible Mesh (No replication at all). Am I missing here something very importand? I double checked everything and replication should actually work… (Altough there were no replication options for the destructible…)
Can please somebody help me with this?

Sincerely,