An alternate method is to edit the /etc/apt/sources.list and change all of the
http://ftp.us.debian.org lines to read http://ftp.de.debian.org. That's a german mirror but it should work without giving you problems. If you comment out the faulty mirrors, you'll reduce the amount of packages available to download and update, so I find it better to change the mirrors as needed so I can continue to get all of the updates I want/need.