Can't connect to LAN world

I want to connect to my sisters LAN world server, but it's not showing up when I go to friends (it's supposed to be under the friends online tab). We are connected to the same Internet, we both have the multiplayer options selected, and we are not far apart (like 5ft away from each other). I'm not sure if it's because I'm using my iPhone, and she's using a Kindle Fire tablet. When I go into one of my worlds, and she goes to friends it shows up on her screen; but why not mine?

I am playing version 15.0.