I cannot join my friends'worlds on minecraft, even with the use cellular data feature on.

I cannot join my friends' worlds in minecraft. I have the use cellular data feature on because we dont have wifi at home, but it still refuses to connect to their worlds. They also play on mobile, so I know it's not bc they have java edition and I have bedrock. Also, I have another issue where I set the world to be a multiplayer world, but as soon as I join the world it gets turned off again and I cant turn it back on. Someone else filed a report about the same thing and it said it's been resolved, but I'm having the same problem so I thought I'd mention it. Thank you for your time!