The columbian server seems not to work and switching to main server doesn't help. Take a look at that thread. It sounds as if you have to change the sources.list file manually.
It helps to run that command
sudo sed -i 's|co.archive.ubuntu.com|archive.ubuntu.com|g' /etc/apt/sources.list
The command replaces all columbian ubuntu archive repositories with the main archive repositories of ubuntu.
Then run
sudo apt update && sudo apt upgrade