Joining on Minecraft Xbox live

me friend and I try to join on Minecraft Xbox live but it will not work. So the problem is that when she tries to join it lets her on for like 5 minutes but then I says that she was disconnected from the sever and then she t does to join again but it says that she was unable to connect to the sever over and over again and when I try to join it says that I was unable to connect to the sever over and over again too so please help fix that!