Person who joined game had a much smaller world boundary

I was on iPad 2 playing a recently converted infinite world (it was smaller on older versions), my brother joined me on local server multiplayer on a motorola moto G. Both running same version of MCPE. His world boundary was very small, even smaller than before the world was created. He could see blue sky like the end of the world always is. When i went beyond his world boundary, it looked like i was floating, the same applied with animals and items there.

What I expected to happen:

My brother have the same world boundary as me.

What actually happened:

His world boundary was very small (smaller than the original non-infinite size)