Ошибка: не удалось разрешить archive.ubuntu.com

Я получаю это не может решить проблему. Я был в открытой сети с последних двух месяцев после новой установки Ubuntu 18.04. Я только что перешел в ЛВС с прокси. Я сделал все настройки, включая обновление файла /etc/resolv.conf, и посмотрел на другие решения этих типов. Никто не работает.

sudo apt-get update
Err:1 https://download.sublimetext.com apt/stable/ InRelease                     
Could not resolve 'download.sublimetext.com'
Err:2 http://security.ubuntu.com/ubuntu bionic-security InRelease                
Could not resolve 'security.ubuntu.com'
Err:3 http://dl.google.com/linux/chrome/deb stable InRelease                     
Could not resolve 'dl.google.com'
Err:4 http://archive.ubuntu.com/ubuntu bionic InRelease                          
Could not resolve 'archive.ubuntu.com'
Err:5 http://ppa.launchpad.net/leaeasy/dde/ubuntu bionic InRelease     
Could not resolve 'ppa.launchpad.net'
Err:6 http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu bionic InRelease
Could not resolve 'ppa.launchpad.net'
Err:7 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
Could not resolve 'archive.ubuntu.com'
Err:8 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
Could not resolve 'archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease  Could not resolve 'security.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/bionic-backports/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/InRelease  Could not resolve 'dl.google.com'
W: Failed to fetch http://ppa.launchpad.net/leaeasy/dde/ubuntu/dists/bionic/InRelease  Could not resolve 'ppa.launchpad.net'
W: Failed to fetch http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu/dists/bionic/InRelease  Could not resolve 'ppa.launchpad.net'
W: Failed to fetch https://download.sublimetext.com/apt/stable/InRelease  Could not resolve 'download.sublimetext.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.