我尝试在我的 Ubuntu 15.04 上获取更新，但如果无法连接到服务器
me@me:~$ sudo apt-get update
Err http://archive.ubuntu.com vivid InRelease
Err http://archive.ubuntu.com vivid-updates InRelease
Err http://archive.ubuntu.com vivid-backports InRelease
Err http://archive.ubuntu.com vivid-security InRelease
Err http://archive.ubuntu.com vivid Release.gpg
Unable to connect to 54.86.15.42:8080:
Err http://archive.ubuntu.com vivid-updates Release.gpg
Unable to connect to 54.86.15.42:8080:
Err http://archive.ubuntu.com vivid-backports Release.gpg
Unable to connect to 54.86.15.42:8080:
Err http://archive.ubuntu.com vivid-security Release.gpg
Unable to connect to 54.86.15.42:8080:
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/vivid/InRelease
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/vivid-updates/InRelease
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/vivid-backports/InRelease
W: …