So I want to play with a friend in other Android device and more 3 friends connected on PC. They on PC can play together without any problem, but I cannot connect to they multiplayer world. The same problem occur with the other friend on smartphone. I cannot even connect to my friend's smartphone world too.

When they try to connect to my world, the following message appears to them "Locating the server" and never connect, but to me, their names appear online. 

When I try to connect to they multiplayer world appears "Unable to Connect to world".