Portable hotspot LAN multiplayer game doesn't work anymore

My son uses his tablet and turns on his hotspot so his friends can join, and after the update he cannot play with them. It lets his 2 friends join but never lets him in..it says he needs to be connected to a wifi connection..I don't understand what is happening when his friends are on his hotspot. please help me..I have a house full of summer boys dying without joining on minecraft lol..Thanks!