Resolvido usando isso:
sudo cd /etc/apt
sudo mv sources.list sources.list.ok
sudo echo <<EOF
deb mirror://mirrors.ubuntu.com/mirrors.txt xenial main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt xenial-updates main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt xenial-backports main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt xenial-security main restricted universe multiverse
EOF > sources.list
sudo apt-get clean
sudo apt-get update
Após a atualização e atualização, você pode reverter seu sources.list para o original !!