I recently updated to The Better Together Update on my Kindle Fire. My friend has Minecraft for Xbox One, but we cannot connect to each other's worlds. I have no idea what is wrong.
Make sure your friend is on the correct version of Minecraft. You mentioned that they are on the Xbox One. Currently, there are now two versions of Minecraft on the Xbox.
- Minecraft: Xbox One Edition
Image to illustrate difference (from the Xbox App):
The Minecraft that is squared in red is the version that allows for cross platform play. The Minecraft: Xbox One Edition game does not allow for cross platform play through the Better Together update, and is only available to former owners of this version so not to lose any progress or achievement history (it is no longer able to be purchased). According to Minecraft.net:
Q: How do I know which version of Minecraft is which?
A: The old version of Minecraft is called Minecraft: Xbox One Edition. The new version is just called Minecraft. You will see the name of the game on the splash-screen when you launch it.
. . .
Q: What is going to happen to the old console edition?
A: The old console edition will not be available for new purchases after the full release of Minecraft on Xbox One and Switch. Existing owners will still be able to access and play the old console version and minigames, but those versions will not receive updates after the official release of Minecraft.
Minecraft: Xbox One Edition does not have the Better Together update. There is an entirely new Minecraft titled Minecraft on Xbox One that does have this update, and as such, this is the game your friend will need in order to play cross platform.