I cannot login in to minecraft. The launcher says "Could not connect to server.". I added MinecraftLauncher to the firewall but still, can't login with any username.

Today I wanted to play Minecraft, but it didn't work. In first intention, I was logged in into minecraft, wanted to join a server, but it gave the error: ""Failed to login: the authentication are currently down for maintenance.". So I restarted minecraft, and after that the computer, but still the same error (also noticed; in the launcher is said; "play offline". But I did still see the server motds when I went to the server selection). So I decided for some reason to log out. But now I can't login anymore. I have really no clue how to fix this so I hope you guys can help me
(Using launcher 2.0.832)