No Explosion Damage Bug

So I want to activate explosions and explosion damage on my server but I don’t know how to and I also don’t know how it caused it. If you shoot for ex. explosive turrets you will see the explosions they make but they don’t do any damage. The explosions are client sided which means that if player 1 shoots a explosive turret at player 2, player 2 won’t see the explosions. Any help?