I'm currently working on a Zombie server. It's currently very alpha, as there is not much stuff in it other than zombies spawning. Also mods and the hud are disabled.
You can join this server anytime via this IP: 22.214.171.124:30123
Also I made a discord server for this if you want to stay updated: https://discord.gg/RHNBEjY
I'm working on adding more stuff to the server. I plan on having a full survival system with the ability to find loot around the map.