LAN graphics glitch

Well it's buggy on my phone. It lags whenever i join a world with my friends on wifi and kicks me out and sometimes the world glitches and the blocks turn weird and not normal. Whenever i try to join a world with my friends on wifi it lags alot and we get disconnected. And sometimes when I'm on my world and people join it, like 20 minutes later my world glitches and the blocks turn weird.