[Solved] 20.3 unable to reach archive.ubuntu.com, Problem sources.list?

[otadmin]

I did a new install of 20.3 una from a USB-stick. Working fine, updated packages to latest but...
Trying to install a new program from repositories fails with
W: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/u ... v/freeciv- data_2.6.2-1_all.deb
Connection failed [IP: 91.189.88.152 80]

I disabled ipv6. apt update and apt upgrade does not produce an error. Update manager still working. Ping 91.189.88.152 80 no response

Found that my sources.list looked strange to me
deb cdrom:[Linux Mint 20.3 _Una_ - Release amd64 20220104]/ focal contrib main

# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching "deb cdrom"
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.

deb http://archive.ubuntu.com/ubuntu una main multiverse universe restricted
deb http://archive.ubuntu.com/ubuntu una-security main multiverse universe rest>

Note: I added the last to lines manually after searching for advice. But still the same error in synaptic-package manager.

Maybe you could post a sample sources.list for una.

[xenopeek]

Please delete that file. Linux Mint does not use /etc/apt/sources.list.
sudo rm -v /etc/apt/sources.list

Linux Mint puts repository configuration in the .list files under /etc/apt/sources.list.d/. There should be an official-package-repositories.list file there. I suggest after deleting the above file you open Software Sources from your menu and click the button to reset configuration to default. That will put back the standard official-package-repositories.list file.

Ubuntu doesn't have a "una" release. See https://linuxmint.com/download_all.php if you want to know the Ubuntu package base release name for Linux Mint 20.3. But you shouldn't need to do edits like these. Remove the one file and then have Software Sources restore default configuration for you. If the problem persists after that we can look further but the cause will then now be mistakes in your repository configuration files.

[otadmin]

Thank you, solved my problem. I followed your advice and apt update I noticed the Ubuntu base release name is "focal". I did not know there is a difference in repositories for una and focal and linux mint relies on Ubuntu for base.

With this newly acquired knowledge the final solution was found in software sources where there are different mirrors for main(una) and base(focal). I had assumed the second to be just for backup and did never look at it. Turned out that my "backup" base mirror was set to a sever in UK which is not reachable. Changed the base(focal) mirror and it is downloading now.
Thanks again, your help is appreciated.