Put the summary of the bug you're having here

What I expected to happen was...:
Playing SMP on Hard difficulty

What actually happened was...:
Mobs spawn at a very low rate if not at all, walking around at night is effortless. I thought it was just snapshots at first. I am running through a dedicated server but have gone over settings multiple times to try and solve.

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...