I am using Ubuntu 20.04. I was facing this issue, and while trying to fix that I am facing new error now. For command
sudo apt-get update
I am getting
Could not connect to archive.ubuntu.com:443 (185.125.190.39). - connect (111: Connection refused)
and
Unable to connect to archive.ubuntu.com
If I try to access https://archive.ubuntu.com/ubuntu from my browser it shows "This site can’t be reached".
I have tried all the solutions mentioned here.
