UPDATE 2: All servers in the network are updated to 1.5.2. Update your Minecraft client, connect and enjoy 🙂
Currently working on an updated version of our server, and will be applied as soon as possible.
In the meantime, to be able to connect and play the easiest way for you is NOT update when asked so by the launcher.
I will update this post when it’s safe for you to update to 1.5.2.
UPDATE 1: Working 1.5.2 version ready and uploading to the server. Expect it to be applied in the next 10 – 15 mins.