Only one friend can join to an other friend's world.

Only one friend can join to a world. If someone is already joined the other person won't be able to connect to the servers regardless of his internet connection, regardless of the computer hes using. Even though it sometimes works most of the time we can't play together (I'm talking about 3 people). The host is using a Xbox, but the two other guy is playing on windows. We all updated our game and it still doesn't work.