The server migration that happened less than two months ago caused the old Mumble server to go offline. By popular request, I've installed a new one! The new server's address is mumble.creeperslab.net, on port 64738. The password requirement has been removed, so you can simply add the new address to your Mumble client and immediately jump in!
For those of you who don't know, Mumble is a voice chat software that allows you to join a room and talk with other members of the Creeper's Lab while you play. It's lightweight and easy to use, so you can keep it in the background while you're busy on something else! You can find more details, including a download link and installation instructions, on the voice chat page. Don't be afraid to ask others in-game if they'd like to join you for a chat!