Multiplayer connection reset/end of stream error

I can't connect to any multiplayer servers.

What I expected to happen was...:
I would log in to a server with no issues
What really happened was...:
All servers on my list displayed "Can't Reach Server" or "Communication Error". Attempting to connect to one results in a "Connection reset" or "End of Stream" error.
Steps to Reproduce:
1. Just clicking multiplayer triggers the bug
2. ...
3. ...