Nearly every time I try joining a new multiplayer server, I have an error saying that the authentification servers are down and I can't join the server. There are only a few exceptions to this, and when I can join a server, every time I retry I can still join whereas those I can't join, it doesn't change either.

I hope you could help me with this, and I don't know if it can help you but my internet connexion is quite good so I don't think it's the reason.