Unable To connect to world Cross Platform

I have been trying to enter my friend's world for sometime now and I can't connect to it, I have already tried to restart my system, close and open the game but it doesn't seem to work. My friend plays on the mobile version, I have added her to my friends list and the world appears as joinable, but when I click to join it loads for some seconds and it says "Unable to connect to world". I want to know how can I fix this.