Ubuntu Server 16.10 - "Repository does not have a release file" & 404s when running apt-get update

I own a VPS instance on DigitalOcean and I have been encountering issues when updating via apt-get. I get both 404s and issues regarding missing release files.

I am running Ubuntu 16.10, which I obtained by running lsb_release -a.

I have never tried to use PPAs and I have never modified my apt sources. However, I do remember fixing this problem once before by making my apt sources look like the ones on my Ubuntu computer, just with the versions changed.

I have read many other posts about the same problem and I have tried a number of solutions. None have worked. When I run apt-get update (as root), I get:

Ign:1 http://us.archive.ubuntu.com/ubuntu yakkety InRelease
Ign:2 http://us.archive.ubuntu.com/ubuntu yakkety-updates InRelease
Ign:3 http://us.archive.ubuntu.com/ubuntu yakkety Release
Ign:4 http://us.archive.ubuntu.com/ubuntu yakkety-updates Release
Ign:5 http://us.archive.ubuntu.com/ubuntu yakkety/universe Sources
Ign:6 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Sources        
Ign:7 http://us.archive.ubuntu.com/ubuntu yakkety/main Sources              
Ign:8 http://us.archive.ubuntu.com/ubuntu yakkety/main amd64 Packages
Ign:9 http://us.archive.ubuntu.com/ubuntu yakkety/main all Packages
Ign:10 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en_US
Ign:11 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en
Ign:12 http://us.archive.ubuntu.com/ubuntu yakkety/restricted amd64 Packages
Ign:13 http://us.archive.ubuntu.com/ubuntu yakkety/restricted all Packages
Ign:14 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en
Ign:15 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en_US
Ign:16 http://security.ubuntu.com/ubuntu yakkety-security InRelease
Ign:17 http://us.archive.ubuntu.com/ubuntu yakkety/universe all Packages
Ign:18 http://us.archive.ubuntu.com/ubuntu yakkety/universe amd64 Packages
Ign:19 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en_US
Ign:20 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en
Ign:21 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Sources
Ign:22 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Sources
Ign:23 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Sources
Ign:24 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main all Packages
Ign:25 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main amd64 Packages
Ign:26 http://security.ubuntu.com/ubuntu yakkety-security Release
Ign:27 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en_US
Ign:28 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en
Ign:29 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted amd64 Packages
Ign:30 http://security.ubuntu.com/ubuntu yakkety-security/main Sources
Ign:31 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted all Packages
Ign:32 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en_US
Ign:33 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en
Ign:34 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe all Packages
Ign:35 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe amd64 Packages
Ign:36 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en
Ign:37 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en_US
Ign:5 http://us.archive.ubuntu.com/ubuntu yakkety/universe Sources
Ign:6 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Sources
Ign:7 http://us.archive.ubuntu.com/ubuntu yakkety/main Sources
Ign:38 http://security.ubuntu.com/ubuntu yakkety-security/restricted Sources
Ign:8 http://us.archive.ubuntu.com/ubuntu yakkety/main amd64 Packages
Ign:9 http://us.archive.ubuntu.com/ubuntu yakkety/main all Packages
Ign:10 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en_US
Ign:11 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en
Ign:12 http://us.archive.ubuntu.com/ubuntu yakkety/restricted amd64 Packages
Ign:13 http://us.archive.ubuntu.com/ubuntu yakkety/restricted all Packages
Ign:14 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en
Ign:15 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en_US
Ign:17 http://us.archive.ubuntu.com/ubuntu yakkety/universe all Packages
Ign:18 http://us.archive.ubuntu.com/ubuntu yakkety/universe amd64 Packages
Ign:39 http://security.ubuntu.com/ubuntu yakkety-security/main amd64 Packages
Ign:19 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en_US
Ign:20 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en
Ign:40 http://security.ubuntu.com/ubuntu yakkety-security/main all Packages
Ign:21 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Sources
Ign:22 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Sources
Ign:23 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Sources
Ign:24 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main all Packages
Ign:25 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main amd64 Packages
Ign:27 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en_US
Ign:28 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en
Ign:29 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted amd64 Packages
Ign:31 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted all Packages
Ign:32 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en_US
Ign:41 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en
Ign:33 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en
Ign:34 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe all Packages
Ign:35 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe amd64 Packages
Ign:36 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en
Ign:37 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en_US
Ign:5 http://us.archive.ubuntu.com/ubuntu yakkety/universe Sources
Ign:6 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Sources
Ign:7 http://us.archive.ubuntu.com/ubuntu yakkety/main Sources
Ign:8 http://us.archive.ubuntu.com/ubuntu yakkety/main amd64 Packages
Ign:42 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en_US
Ign:9 http://us.archive.ubuntu.com/ubuntu yakkety/main all Packages
Ign:10 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en_US
Ign:11 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en
Ign:12 http://us.archive.ubuntu.com/ubuntu yakkety/restricted amd64 Packages
Ign:43 http://security.ubuntu.com/ubuntu yakkety-security/restricted all Packages
Ign:13 http://us.archive.ubuntu.com/ubuntu yakkety/restricted all Packages
Ign:14 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en
Ign:15 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en_US
Ign:17 http://us.archive.ubuntu.com/ubuntu yakkety/universe all Packages
Ign:18 http://us.archive.ubuntu.com/ubuntu yakkety/universe amd64 Packages
Ign:19 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en_US
Ign:20 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en
Ign:44 http://security.ubuntu.com/ubuntu yakkety-security/restricted amd64 Packages
Ign:21 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Sources
Ign:22 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Sources
Ign:23 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Sources
Ign:24 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main all Packages
Ign:25 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main amd64 Packages
Ign:27 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en_US
Ign:28 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en
Ign:29 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted amd64 Packages
Ign:31 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted all Packages
Ign:45 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en
Ign:32 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en_US
Ign:33 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en
Ign:34 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe all Packages
Ign:35 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe amd64 Packages
Ign:36 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en
Ign:37 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en_US
Ign:5 http://us.archive.ubuntu.com/ubuntu yakkety/universe Sources
Ign:6 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Sources
Ign:46 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en_US
Ign:7 http://us.archive.ubuntu.com/ubuntu yakkety/main Sources
Ign:8 http://us.archive.ubuntu.com/ubuntu yakkety/main amd64 Packages
Ign:9 http://us.archive.ubuntu.com/ubuntu yakkety/main all Packages
Ign:10 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en_US
Ign:11 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en
Ign:30 http://security.ubuntu.com/ubuntu yakkety-security/main Sources
Ign:12 http://us.archive.ubuntu.com/ubuntu yakkety/restricted amd64 Packages 
Ign:13 http://us.archive.ubuntu.com/ubuntu yakkety/restricted all Packages   
Ign:14 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en
Ign:15 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en_US
Ign:17 http://us.archive.ubuntu.com/ubuntu yakkety/universe all Packages
Ign:18 http://us.archive.ubuntu.com/ubuntu yakkety/universe amd64 Packages
Ign:19 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en_US
Ign:20 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en
Ign:38 http://security.ubuntu.com/ubuntu yakkety-security/restricted Sources
Ign:21 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Sources
Ign:22 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Sources
Ign:23 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Sources
Ign:24 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main all Packages
Ign:25 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main amd64 Packages
Ign:27 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en_US
Ign:28 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en
Ign:29 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted amd64 Packages
Ign:31 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted all Packages
Ign:39 http://security.ubuntu.com/ubuntu yakkety-security/main amd64 Packages
Ign:32 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en_US
Ign:33 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en
Ign:34 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe all Packages
Ign:35 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe amd64 Packages
Ign:36 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en
Ign:37 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en_US
Ign:40 http://security.ubuntu.com/ubuntu yakkety-security/main all Packages
Ign:5 http://us.archive.ubuntu.com/ubuntu yakkety/universe Sources
Ign:6 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Sources
Ign:7 http://us.archive.ubuntu.com/ubuntu yakkety/main Sources
Ign:8 http://us.archive.ubuntu.com/ubuntu yakkety/main amd64 Packages
Ign:9 http://us.archive.ubuntu.com/ubuntu yakkety/main all Packages
Ign:10 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en_US
Ign:41 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en
Ign:11 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en
Ign:12 http://us.archive.ubuntu.com/ubuntu yakkety/restricted amd64 Packages
Ign:13 http://us.archive.ubuntu.com/ubuntu yakkety/restricted all Packages
Ign:14 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en
Ign:15 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en_US
Ign:17 http://us.archive.ubuntu.com/ubuntu yakkety/universe all Packages
Ign:18 http://us.archive.ubuntu.com/ubuntu yakkety/universe amd64 Packages
Ign:19 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en_US
Ign:20 http://us.archive.ubuntu.com/ubuntu yakkety/universe Translation-en
Ign:21 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Sources
Ign:42 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en_US
Ign:22 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Sources
Ign:23 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Sources
Ign:24 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main all Packages
Ign:25 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main amd64 Packages
Ign:27 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en_US
Ign:28 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en
Ign:29 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted amd64 Packages
Ign:31 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted all Packages
Ign:32 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en_US
Ign:43 http://security.ubuntu.com/ubuntu yakkety-security/restricted all Packages
Ign:33 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en
Ign:34 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe all Packages
Ign:35 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe amd64 Packages
Ign:44 http://security.ubuntu.com/ubuntu yakkety-security/restricted amd64 Packages
Ign:36 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en
Ign:37 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Translation-en_US
Err:5 http://us.archive.ubuntu.com/ubuntu yakkety/universe Sources
  404  Not Found [IP: 91.189.91.26 80]
Ign:6 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Sources
Ign:7 http://us.archive.ubuntu.com/ubuntu yakkety/main Sources
Ign:8 http://us.archive.ubuntu.com/ubuntu yakkety/main amd64 Packages
Ign:9 http://us.archive.ubuntu.com/ubuntu yakkety/main all Packages
Ign:10 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en_US
Ign:11 http://us.archive.ubuntu.com/ubuntu yakkety/main Translation-en
Ign:45 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en
Ign:12 http://us.archive.ubuntu.com/ubuntu yakkety/restricted amd64 Packages
Ign:13 http://us.archive.ubuntu.com/ubuntu yakkety/restricted all Packages
Ign:14 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en
Ign:15 http://us.archive.ubuntu.com/ubuntu yakkety/restricted Translation-en_US
Err:21 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Sources
  404  Not Found [IP: 91.189.91.26 80]
Ign:22 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Sources
Ign:23 http://us.archive.ubuntu.com/ubuntu yakkety-updates/universe Sources
Ign:24 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main all Packages
Ign:25 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main amd64 Packages
Ign:46 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en_US
Ign:27 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en_US
Ign:28 http://us.archive.ubuntu.com/ubuntu yakkety-updates/main Translation-en
Ign:29 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted amd64 Packages
Ign:30 http://security.ubuntu.com/ubuntu yakkety-security/main Sources
Ign:31 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted all Packages
Ign:32 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en_US
Ign:33 http://us.archive.ubuntu.com/ubuntu yakkety-updates/restricted Translation-en
Ign:38 http://security.ubuntu.com/ubuntu yakkety-security/restricted Sources
Ign:39 http://security.ubuntu.com/ubuntu yakkety-security/main amd64 Packages
Ign:40 http://security.ubuntu.com/ubuntu yakkety-security/main all Packages
Ign:41 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en
Ign:42 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en_US
Ign:43 http://security.ubuntu.com/ubuntu yakkety-security/restricted all Packages
Ign:44 http://security.ubuntu.com/ubuntu yakkety-security/restricted amd64 Packages
Ign:45 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en
Ign:46 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en_US
Ign:30 http://security.ubuntu.com/ubuntu yakkety-security/main Sources
Ign:38 http://security.ubuntu.com/ubuntu yakkety-security/restricted Sources
Ign:39 http://security.ubuntu.com/ubuntu yakkety-security/main amd64 Packages
Ign:40 http://security.ubuntu.com/ubuntu yakkety-security/main all Packages
Ign:41 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en
Ign:42 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en_US
Ign:43 http://security.ubuntu.com/ubuntu yakkety-security/restricted all Packages
Ign:44 http://security.ubuntu.com/ubuntu yakkety-security/restricted amd64 Packages
Ign:45 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en
Ign:46 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en_US
Ign:30 http://security.ubuntu.com/ubuntu yakkety-security/main Sources
Ign:38 http://security.ubuntu.com/ubuntu yakkety-security/restricted Sources
Ign:39 http://security.ubuntu.com/ubuntu yakkety-security/main amd64 Packages
Ign:40 http://security.ubuntu.com/ubuntu yakkety-security/main all Packages
Ign:41 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en
Ign:42 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en_US
Ign:43 http://security.ubuntu.com/ubuntu yakkety-security/restricted all Packages
Ign:44 http://security.ubuntu.com/ubuntu yakkety-security/restricted amd64 Packages
Ign:45 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en
Ign:46 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en_US
Err:30 http://security.ubuntu.com/ubuntu yakkety-security/main Sources
  404  Not Found [IP: 91.189.88.161 80]
Ign:38 http://security.ubuntu.com/ubuntu yakkety-security/restricted Sources
Ign:39 http://security.ubuntu.com/ubuntu yakkety-security/main amd64 Packages
Ign:40 http://security.ubuntu.com/ubuntu yakkety-security/main all Packages
Ign:41 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en
Ign:42 http://security.ubuntu.com/ubuntu yakkety-security/main Translation-en_US
Ign:43 http://security.ubuntu.com/ubuntu yakkety-security/restricted all Packages
Ign:44 http://security.ubuntu.com/ubuntu yakkety-security/restricted amd64 Packages
Ign:45 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en
Ign:46 http://security.ubuntu.com/ubuntu yakkety-security/restricted Translation-en_US
Reading package lists... Done
W: The repository 'http://us.archive.ubuntu.com/ubuntu yakkety Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://us.archive.ubuntu.com/ubuntu yakkety-updates Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://security.ubuntu.com/ubuntu yakkety-security Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/yakkety/universe/source/Sources  404  Not Found [IP: 91.189.91.26 80]
E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/yakkety-updates/main/source/Sources  404  Not Found [IP: 91.189.91.26 80]
E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/yakkety-security/main/source/Sources  404  Not Found [IP: 91.189.88.161 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.

And my /etc/apt/sources.list…

## Note, this file is written by cloud-init on first boot of an instance
## modifications made here will not survive a re-bundle.
## if you wish to make changes you can:
## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
##     or do the same in user-data
## b.) add sources in /etc/apt/sources.list.d
## c.) make changes to template file /etc/cloud/templates/sources.list.tmpl

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ yakkety main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ yakkety main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ yakkety-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ yakkety-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://us.archive.ubuntu.com/ubuntu/ yakkety universe
deb-src http://us.archive.ubuntu.com/ubuntu/ yakkety universe
deb http://us.archive.ubuntu.com/ubuntu/ yakkety-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ yakkety-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://nyc3.clouds.archive.ubuntu.com/ubuntu/ yakkety multiverse
#deb-src http://nyc3.clouds.archive.ubuntu.com/ubuntu/ yakkety multiverse
#deb http://nyc3.clouds.archive.ubuntu.com/ubuntu/ yakkety-updates multiverse
#deb-src http://nyc3.clouds.archive.ubuntu.com/ubuntu/ yakkety-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://nyc3.clouds.archive.ubuntu.com/ubuntu/ yakkety-backports main restricted universe multiverse
#deb-src http://nyc3.clouds.archive.ubuntu.com/ubuntu/ yakkety-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu yakkety-security main restricted
deb-src http://security.ubuntu.com/ubuntu yakkety-security main restricted
#deb http://security.ubuntu.com/ubuntu yakkety-security universe
#deb-src http://security.ubuntu.com/ubuntu yakkety-security universe
#deb http://security.ubuntu.com/ubuntu yakkety-security multiverse
#deb-src http://security.ubuntu.com/ubuntu yakkety-security 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 yakkety partner
# deb-src http://archive.canonical.com/ubuntu yakkety partner

I would like to avoid upgrading Ubuntu versions at all costs since this server runs a ton and I don’t have the time to fix issues. Any ideas would be greatly appreciated!