情况：我有一台 Zentyal 服务器，上面有 3 个虚拟机（Qemu），由 KVM 管理器管理。所有虚拟机都在 Ubuntu 18.04.03 LTS 上运行
主机：Zentyal 6.0.1
VM1：Ubuntu 服务器
VM2：Zentyal 6.0.1
VM3：Ubuntu 服务器
问题：当更新 --> 升级时，客人可以更新/升级而不会出现任何其他问题。只需 apt-get update --> apt-get upgrade。即可。
*当我更新主机时，我收到消息
Fehl:2 http://security.ubuntu.com/ubuntu bionic-security InRelease
Zeitüberschreitung bei Verbindung [IP: 91.189.88.174 80]
连接超时
主机和 VM2 具有相同的配置，但 VM2 在更新/升级时没有问题
这是来自 Host 的 source.list
# deb cdrom:[Ubuntu-Server 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ bionic extras main restricted
# deb cdrom:[Ubuntu-Server 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ bionic extras main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://de.archive.ubuntu.com/ubuntu/ bionic main restricted
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://de.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://de.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic universe
deb http://de.archive.ubuntu.com/ubuntu/ bionic-updates universe
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-updates universe
## 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://de.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://de.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
# deb-src http://de.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://de.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
# deb-src http://de.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://archive.zentyal.org/zentyal 6.0 main
deb-src 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
有人有想法吗？
谢谢！