当我尝试在 Ubuntu 14.04 机器上进行更新时，我注意到以下错误。我记得我上次尝试时它工作正常。
sudo apt-get update
Err http://extras.ubuntu.com trusty InRelease
Err http://extras.ubuntu.com trusty Release.gpg
Cannot initiate the connection to extras.ubuntu.com:80 (2001:67c:1360:8c01::23). - connect (101: Network is unreachable) [IP: 2001:67c:1360:8c01::23 80]
Err http://us.archive.ubuntu.com trusty InRelease
Err http://us.archive.ubuntu.com trusty-updates InRelease
Err http://us.archive.ubuntu.com trusty-backports InRelease
Err http://us.archive.ubuntu.com trusty-proposed InRelease
Err http://us.archive.ubuntu.com trusty Release.gpg
Cannot initiate the connection to us.archive.ubuntu.com:80 (2001:67c:1562::15). - connect (101: Network is unreachable) [IP: 2001:67c:1562::15 80]
Err http://us.archive.ubuntu.com trusty-updates Release.gpg
Cannot initiate the connection to us.archive.ubuntu.com:80 (2001:67c:1562::15). - connect …