Edit sources.list
nano /etc/apt/sources.list
Replace it with:
deb http://ftp.debian.org/debian jessie main contrib
deb http://ftp.debian.org/debian jessie-updates main contrib
deb http://security.debian.org jessie/updates main contrib
To fix 0% download progress issue, edit gai.conf
nano /etc/gai.conf
uncomment this line:
precedence ::ffff:0:0/96 100
To fix 404 issues:
echo 'Acquire::Check-Valid-Until no;' > /etc/apt/apt.conf.d/99no-check-valid-until