I'm having trouble connecting to the world of other friends

hello, i've been having a problem for a long time, i can't connect to my friends' world, nor can they connect to mine. Whenever we try the following message appears "it was not possible to connect to the world". Today, I tried again, it worked, but when I left the world and tried to go back, the same message appeared again. All my friends bought their games and each one plays on their own cell phone. I even thought it could be the different cell phone brands, since mine is an IOS and theirs are ANDROIDS. Please help us with this, we like the game very much and we don't want to go so far as to ask for a refund. IT'S INADIMICIBLE that paying R $ 30.00 we still cointinuate with the same problem

edit: I can connect to servers. But in other people's world, I can't