Today (4/15/15) at 12:00pm EDT, the Epic Games Launcher and Marketplace services will be undergoing a regular maintenance. The services will be offline for approximately one hour, until 1:00pm EDT.
During this time, the Marketplace will display as “Closed”, and other pages will show as being disconnected. New installations and updates will be unavailable until the maintenance is complete. However, you will still be able to access your existing installs.
Thanks for your patience!