Can't connect to my server (End of stream)

[Hydz]

So I tried to make a server for me and my friend to play on. The server works fine and portforwarding, firewall stuff etc. is all setup correctly. But when I, or anyone else, try to connect to the server, it instantly disconnects and gives the end of stream error. 

Looking at the console, I'm pretty positive this is the reason: "java.io.IOException: Received string length longer than maximum allowed (6656 > 16)". However I have no idea how to fix it. I tried using the /cofh killall command in the case that it was a mob. The server gives me back this: "Removed 2 hostile entities. (ºc2ºfxºeEndermanºf)". 

Please someone help me with this, I have no idea how to make this work.

[E4RU]

Please add full log from the server where this error occured. Use pastebin to give us the log that we need to assist you.