I know some people will post questions and threads on how to switch back and ask why they can't play in this section so I'm making this post.
(This is only in effect until Optical updates the server to 1.8.)
If you've updated and switched to version 1.8 and there is a Red X over the connection bars, that means that you can't play unless you wait for the server to update or switch back. If you don't feel like waiting, this is how you switch back:
Open Minecraft Launcher
Click "Edit Profile" in the bottom left corner of the launcher.
Select the drop down next to "Use Version:"
Scroll down and select "Release 1.7.10"
Click "Save Profile" and play.
Hope this helped.
