403アラスカアンカレッジで禁止された更新エラーが発生しました。

奇妙に見えますが、アンカレッジでのみこれが起こります。 Ubuntu 18.04 LTSをアップデートして「sudo apt update」を実行しようとすると、次のような結果が表示されます。

E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/bionic-security/main/binary-amd64/Packages 403  Forbidden [IP: 91.189.91.38 80] 
E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/bionic-updates/main/binary-amd64/Packages 403  Forbidden [IP: 91.189.91.38 80] 
E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/bionic/universe/binary-i386/Packages 403  Forbidden [IP: 91.189.91.38 80] 
E: Some index files failed to download. They have been ignored, or old ones used instead.`

これは新しくインストールされたもので、アンカレッジ内の他の仮想マシンで同じエラーで複数回試行されました。

私もカナダの他のミラーサイトを試してみましたが、成功しませんでした。

理解できないことですが、コロラド州の他のサイトでも同じことをしましたが、うまくいきました。どんなアイデアがありますか？

これは私の/etc/apt/sources.listです。

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner

deb http://security.ubuntu.com/ubuntu bionic-security main restricted
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse