操作系统：Ubuntu 16.04 LTS 网络：LAN（使用 fast.com 确认为 25Mbps）
sudo apt-get upgrade
上述命令的下载时间太长。我尝试按照这线程。速度慢的问题仍未解决，并且我收到新的错误
PS：我尝试了不同的 Ubuntu 服务器，但问题仍然存在。
$ time sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
freepats gstreamer1.0-plugins-bad-faad gstreamer1.0-plugins-bad-videoparsers libavresample-ffmpeg2 libbs2b0
libde265-0 libflite1 libfluidsynth1 libgstreamer-plugins-bad1.0-0 libgtkglext1 libllvm4.0 libmimic0
libmjpegutils-2.1-0 libmms0 libmpeg2encpp-2.1-0 libmplex2-2.1-0 libofa0 libsodium18 libsoundtouch1 libspandsp2
libsrtp0 libtbb2 libwildmidi-config libwildmidi1 libzbar0 libzmq5 linux-image-4.10.0-28-generic
linux-image-extra-4.10.0-28-generic linux-signed-image-4.10.0-28-generic
Use 'sudo apt autoremove' to remove them.
The following packages have been kept back:
libmm-glib0 libqmi-proxy linux-generic-hwe-16.04 linux-headers-generic-hwe-16.04 linux-image-generic-hwe-16.04
linux-signed-generic-hwe-16.04 linux-signed-image-generic-hwe-16.04 modemmanager
The following packages will be upgraded:
cpp-5 curl distro-info-data firefox firefox-locale-en fwupdate fwupdate-signed g++-5 gcc-5 gcc-5-base
gcc-5-base:i386 gfortran-5 gir1.2-javascriptcoregtk-4.0 gir1.2-webkit2-4.0 gnome-software gnome-software-common
grub-common grub-efi-amd64 grub-efi-amd64-bin grub-efi-amd64-signed grub2-common iproute2 libasan2 libatomic1
libcc1-0 libcilkrts5 libcurl3 libcurl3-gnutls libegl1-mesa libfwup0 libgbm1 libgcc-5-dev libgfortran-5-dev
libgfortran3 libgl1-mesa-dev libgl1-mesa-dri libgl1-mesa-dri:i386 libgl1-mesa-glx libgl1-mesa-glx:i386
libglapi-mesa libglapi-mesa:i386 libgles2-mesa libgomp1 libitm1 libjavascriptcoregtk-4.0-18 liblsan0
libmbim-glib4 libmbim-proxy libmpx0 libosmesa6 libosmesa6:i386 libpam-systemd libpython2.7 libpython2.7-minimal
libpython2.7-stdlib libquadmath0 libstdc++-5-dev libstdc++6 libstdc++6:i386 libsystemd0 libsystemd0:i386
libtasn1-6 libtasn1-6:i386 libtsan0 libubsan0 libudev1 libudev1:i386 libwayland-egl1-mesa libwebkit2gtk-4.0-37
libwebkit2gtk-4.0-37-gtk2 libxatracker2 light-themes linux-firmware mesa-common-dev mesa-va-drivers
mesa-vdpau-drivers python2.7 python2.7-minimal suru-icon-theme systemd systemd-sysv thunderbird
thunderbird-gnome-support thunderbird-locale-en thunderbird-locale-en-us ubuntu-artwork ubuntu-mobile-icons
ubuntu-mono ubuntu-software udev update-notifier update-notifier-common
92 upgraded, 0 newly installed, 0 to remove and 8 not upgraded.
Need to get 243 MB of archives.
After this operation, 10.4 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libpam-systemd amd64 229-4ubuntu21.1 [116 kB]
Get:2 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libudev1 amd64 229-4ubuntu21.1 [54.9 kB]
Get:3 http://archive.ubuntu.com/ubuntu xenial-updates/main i386 libudev1 i386 229-4ubuntu21.1 [58.0 kB]
Get:4 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 udev amd64 229-4ubuntu21.1 [992 kB]
Get:5 http://archive.ubuntu.com/ubuntu xenial-updates/main i386 libsystemd0 i386 229-4ubuntu21.1 [222 kB]
Get:6 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libsystemd0 amd64 229-4ubuntu21.1 [205 kB]
Err:7 http://security.ubuntu.com/ubuntu xenial-security/main amd64 systemd amd64 229-4ubuntu21.1
Connection failed [IP: 91.189.88.149 80]
Get:8 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 systemd-sysv amd64 229-4ubuntu21.1 [12.2 kB]
Get:9 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libpython2.7 amd64 2.7.12-1ubuntu0~16.04.3 [1,070 kB]
Get:10 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 python2.7 amd64 2.7.12-1ubuntu0~16.04.3 [224 kB]
Err:11 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libpython2.7-stdlib amd64 2.7.12-1ubuntu0~16.04.3
Connection failed [IP: 91.189.88.162 80]
Err:7 http://security.ubuntu.com/ubuntu xenial-security/main amd64 systemd amd64 229-4ubuntu21.1
Connection failed [IP: 91.189.88.149 80]
3% [Waiting for headers]