The No Mo Culling mod, formerly known as Zombie Fix, is a mod that fixes zombies disappearing over a count of 500 and when being kited. This is an annoying bug with the game and this mod seeks to fix the issue. Here are the steps to install the fix on your server.
1. Download the files from the official github. Simply click the NetworkZombiePacker.class
and ZombieCountOptimiser.class
2. Once you have the files downloaded, open the File Manager
3. Navigate to /server-files/java/zombie/popman
4. Right click and upload the two previously downloaded files
5. These files will replace the default files.
6. Restart the server