everytime i join a multiplayer server,it logs me out

What I expected to happen was
that id be in that server until i quit to title

What actually happened was
sometimes it said "unknown host" or "internal exception: io.netty.handler,timeout.read.timeout.exception" and it sometines tells me to restart my game

Steps to Reproduce:
1. i don't know,but i have wifi,just log in
2. join a server,my problem might happen to other people
3. I think this is a wifi thing problem