friends are unable to join my world

verytime i create a world and try to invite friends they are unable to join yet the weird thing is that i can join them on their world. microsoft looked at my console and we did everything we could but they say my console is in ideal perfect condition but its weird the game doesnt let me allow friends to join in. the game is updated and we all have the same version but still i cannot let friends into my world as they always get the message unable to join world. please fix the bug asap so my friends can join me please