Debian HC4 NASはホストを確認できません。

stackoverflowとLinuxに初めてアクセスし、HC4にNASを設定し、現在のSteamキャッシュを設定しようとしています。 dockerをインストールした後にネットワーク管理者をインストールしようとしましたが、次のエラーが返されて問題が発生しました。

W: Failed to fetch http://deb.debian.org/debian/dists/stable/InRelease  Could not resolve 'deb.debian.org'
W: Failed to fetch http://deb.debian.org/debian/dists/buster-updates/InRelease  Could not resolve 'deb.debian.org'
W: Failed to fetch http://deb.debian.org/debian-security/dists/buster/updates/InRelease  Could not resolve 'deb.debian.org'
W: Failed to fetch http://ftp.debian.org/debian/dists/buster-backports/InRelease  Could not resolve 'ftp.debian.org'
W: Failed to fetch https://download.docker.com/linux/debian/dists/buster/InRelease  Could not resolve 'download.docker.com'
W: Failed to fetch http://packages.openmediavault.org/public/dists/erasmus/InRelease  Could not resolve 'packages.openmediavault.org'
W: Failed to fetch https://openmediavault-plugin-developers.github.io/packages/debian/dists/usul/InRelease  Could not resolve 'openmediavault-plugin-developers.github.io'
W: Failed to fetch http://packages.openmediavault.org/public/dists/usul/InRelease  Could not resolve 'packages.openmediavault.org'
W: Failed to fetch http://ppa.linuxfactory.or.kr/dists/buster/InRelease  Could not resolve 'ppa.linuxfactory.or.kr'
W: Some index files failed to download. They have been ignored, or old ones used instead.
W: Target Packages (stable/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:24 and /etc/apt/sources.list.d/docker.list:1
W: Target Translations (stable/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:24 and /etc/apt/sources.list.d/docker.list:1
W: Target Packages (stable/binary-arm64/Packages) is configured multiple times in /etc/apt/sources.list.d/docker.list:1 and /etc/apt/sources.list.d/omvextras.list:2
W: Target Packages (stable/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:24 and /etc/apt/sources.list.d/omvextras.list:2
W: Target Translations (stable/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:24 and /etc/apt/sources.list.d/omvextras.list:2

これで、apt-get update と apt-get install network-manager の戻り値でこれらのエラーが発生します。

Reading package lists... Done
Building dependency tree
Reading state information... Done
Package network-manager is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'network-manager' has no installation candidate

私はこれをたくさん台無しにしたので、ここに私のソースリストがあります：

#------------------------------------------------------------------------------#
#                   OFFICIAL DEBIAN REPOS
#------------------------------------------------------------------------------#

###### Debian Main Repos
deb http://deb.debian.org/debian stable main
deb-src http://deb.debian.org/debian stable main

deb http://deb.debian.org/debian buster-updates main
deb-src http://deb.debian.org/debian buster-updates main

deb http://deb.debian.org/debian-security/ buster/updates main
deb-src http://deb.debian.org/debian-security/ buster/updates main

deb http://ftp.debian.org/debian buster-backports main
deb-src http://ftp.debian.org/debian buster-backports main

#------------------------------------------------------------------------------#
#                      UNOFFICIAL  REPOS
#------------------------------------------------------------------------------#

###### 3rd Party Binary Repos
###Docker CE
deb [arch=amd64] https://download.docker.com/linux/debian buster stable

###openmediavault
deb http://packages.openmediavault.org/public erasmus main
deb-src http://packages.openmediavault.org/public erasmus main

助けやご案内をいただきありがとうございます。