Update not working

Hi,
I've not used my PC for several weeks and now update is not working, although it was before.
I get messages saying I'm off-line but I'm not, I'm sending this post!
I cannot tick the 3 boxes on the "Software & Updates" tab, i.e. Important security updates (bionic security), Recommended etc...
Help please.

Is your update set to get updates from 'Main Server'? The unchecked items is a GUI bug that has been present in Ubuntu for many iterations. It does not mean you won't get security updates - they still come through.

The only updates you can't get are in respect of 3rd Party software/drivers which are not listed as Ubuntu Partners.

Have you tried updating via CLI?

Code:

sudo apt update
sudo apt upgrade -y
sudo apt dist-upgrade -y
sudo apt autoclean -y
sudo update-grub


Most applications will be upgraded without a need to reboot or reload. However to switch to the new Kernal you do have to reboot.

Code:

sudo systemctl reboot