Ubuntu 20.04 LTS Focal apt-get update not working

Question

So, here is my problem. I know it has been reported a lot, but somehow, it is kinda different.

I'm using Linux Ubuntu 20.04 LTS on a VM, and was able to successfully install the image with no problems.

syspass@syspass:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04 LTS
Release:        20.04
Codename:       focal

Now, I'm trying to update the repo to be able to install some packages that I need to be able to deploy some systems on the the machine. However, I'm not able to due to a Connection Error

syspass@syspass:~$ sudo apt-get update
Err:1 http://archive.ubuntu.com/ubuntu focal InRelease
  Connection failed [IP: 91.189.88.152 80]
Err:2 http://archive.ubuntu.com/ubuntu focal-updates InRelease
  Connection failed [IP: 91.189.88.152 80]
Err:3 http://archive.ubuntu.com/ubuntu focal-backports InRelease
  Connection failed [IP: 91.189.88.152 80]
Err:4 http://archive.ubuntu.com/ubuntu focal-security InRelease
  Connection failed [IP: 91.189.88.152 80]
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal/InRelease  Connection failed [IP: 91.189.88.152 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease  Connection failed [IP: 91.189.88.152 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease  Connection failed [IP: 91.189.88.152 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-security/InRelease  Connection failed [IP: 91.189.88.152 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.

So, I did some digging, and found that the IP Address is indeed reachable from the VM (Note: ping is blocked over the network for security purposes)

syspass@syspass:~$ nslookup archive.ubuntu.com
Server:         127.0.0.53
Address:        127.0.0.53#53

Non-authoritative answer:
Name:   archive.ubuntu.com
Address: 91.189.88.142
Name:   archive.ubuntu.com
Address: 91.189.88.152
Name:   archive.ubuntu.com
Address: 2001:67c:1360:8001::23
Name:   archive.ubuntu.com
Address: 2001:67c:1360:8001::24

syspass@syspass:/var/tmp$ tracepath -4 -b archive.ubuntu.com
 1?: [LOCALHOST]                      pmtu 1500
 1:  _gateway (10.8.4.254)                                 1.047ms
 1:  _gateway (10.8.4.254)                                 1.068ms
 2:  10.8.6.1 (10.8.6.1)                                   1.030ms
 3:  10.8.5.2 (10.8.5.2)                                   1.446ms
 4:  10.2.240.254 (10.2.240.254)                           2.673ms
 5:  no reply
 6:  no reply
 7:  197.246.5.49 (197.246.5.49)                          11.161ms pmtu 1492
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  actiontoad.canonical.com (91.189.88.152)            131.035ms reached
     Resume: pmtu 1492 hops 14 back 14

So, I decided to do a bit of further digging, and found that the required resource is indeed reachable!

syspass@syspass:~$ wget http://archive.ubuntu.com/ubuntu/dists/focal/InRelease
--2020-12-08 09:39:29--  http://archive.ubuntu.com/ubuntu/dists/focal/InRelease
Resolving archive.ubuntu.com (archive.ubuntu.com)... 91.189.88.152, 91.189.88.142, 2001:67c:1360:8001::24, ...
Connecting to archive.ubuntu.com (archive.ubuntu.com)|91.189.88.152|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 264892 (259K)
Saving to: ‘InRelease’

InRelease                          100%[=============================================================>] 258.68K   345KB/s    in 0.8s

2020-12-08 09:39:30 (345 KB/s) - ‘InRelease’ saved [264892/264892]

syspass@syspass:~$ curl -vvv http://archive.ubuntu.com/ubuntu/dists/focal/InRelease --HEAD
*   Trying 91.189.88.142:80...
* TCP_NODELAY set
* Connected to archive.ubuntu.com (91.189.88.142) port 80 (#0)
> HEAD /ubuntu/dists/focal/InRelease HTTP/1.1
> Host: archive.ubuntu.com
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
HTTP/1.1 200 OK
< Date: Tue, 08 Dec 2020 09:42:06 GMT
Date: Tue, 08 Dec 2020 09:42:06 GMT
< Server: Apache/2.4.29 (Ubuntu)
Server: Apache/2.4.29 (Ubuntu)
< Last-Modified: Thu, 23 Apr 2020 17:34:17 GMT
Last-Modified: Thu, 23 Apr 2020 17:34:17 GMT
< ETag: "40abc-5a3f8a874d840"
ETag: "40abc-5a3f8a874d840"
< Accept-Ranges: bytes
Accept-Ranges: bytes
< Content-Length: 264892
Content-Length: 264892
< Cache-Control: max-age=0, proxy-revalidate
Cache-Control: max-age=0, proxy-revalidate
< Expires: Tue, 08 Dec 2020 09:42:06 GMT
Expires: Tue, 08 Dec 2020 09:42:06 GMT

<
* Connection #0 to host archive.ubuntu.com left intact

My /etc/apt/sources.list file is below as well in case it can help:

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

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

Solution

After deeper investigation, I found that the apt-get was blocked on a perimeter firewall. After allowing the traffic for apt-get application, everything worked fine.