Unable to connect to server

I can login and select the Realms option on my PC.  The launcher allows me to select the realm (Snowy Mountain, Underground City), but when I select Play it spins the connecting to the realm screen for a while before reporting that it cannot connect to the server, I have attached a screenshot of the error message.  It will not let me download the Realm either, when I attempt that it just stayts in the Preparing Download screen.