Can't load into a specific server with one account, but I can load into the same server on a different account

Can't load into a specific server with one account, but I can load into the same server on a different account

What I expected to happen was...:
I log into Minecraft and load into a server to play.

What actually happened was...:
I can't play on the one specific server that I own (other servers are fine). It gets stuck on 'loading terrain' and I just have to close the game. I can log into the server on another account that I own, and other people can play on it as well. It's just the original account that owns the server that can't join. 

Steps to Reproduce:
I have no idea what happened that caused this. I just tried to play and then this started happening.