Can't join people with the same WiFi

When I try to join my brother it keeps saying 'disconnected from world'. When my friends come over my house to play Minecraft and try's to join me it also says 'disconnected from world' but when they're at they're house and try to join me, it let them join me in Minecraft. I think Minecraft should fix the multiplayer thing in Minecraft PE. It also happen to other people.