ubuntu apt-get is always wrong

sudo apt-get update

update, the following appears: hash sum mismatch
soft execution:

sudo rm -fR /var/lib/apt/lists/*
sudo apt-get clean  
sudo apt-get update --fix-missing  

still appears, hash sum mismatch

try again:

sudo apt-get update -o Acquire::http::No-Cache=True
sudo apt-get update && sudo apt-get upgrade

at this time, it is gone.
but the actual source code IP cannot be found. Err
has changed ali source and 163source. There are all kinds of errors.
ubuntu version is 14.04. What is the reason for
? Is it because of the network or the replacement of the address source?