Unable to join friends worlds

I am unable to join friends in minecraft. I can join LAN network worlds and public servers like “The Hive”. Yet cannot join friends worlds including my own children (so yes i have checked they have multiplayer enabled). Im using IOS minecraft, updated and reinstalled minecraft. Running the latest IOS. I have logged out and back in… i have made sure my cellular connection is on. I have reset my device. I have removed friends and re added them. “Im still unable to connect to world. I have also tried using alternate Microsoft accounts on iphone and it still wont work… HELP