error playing multiplayer on Xbox live

I have had a problem for a while at 1.12.1, I recently created an xbox live account to play minecraft pe with my friends, but when I open the world and release them to enter appears '' unable to connect to the world '' The solution is everywhere and I found nothing, this problem only happens when I play with friends at a distance, when and local multiplayer they come in normally, but when they are at home, I or they can not play together in the same world. can you help me ?

thank you for your attention, you guys do a great job <3