Why did I lose access to the Internet on Linux wether using WiFi or Ethernet?

Question

I use Ubuntu on my laptop for months without any issues. Today I was unable to connect to my WiFi router. All other devices could connect so I figured that it was not an issue with my ISP nor the router.

I tried to connect my laptop using an Ethernet cable but without success.

I finally booted from a USB flash drive that had an Ubuntu image to see if my wireless adapter still worked, and it did.

Answer 1

I found out that a VPN Kill Switch was active (even though my VPN client wasn't running and couldn't be started) by opening a Terminal session and typing:

nmcli connection show --active

Then I deleted the Kill Switch connections like so (replace the last argument with the name of your kill switch connections) :

nmcli connection delete xxxxx-killswitch

nmcli connection delete xxxx-ipv6leak-protection

Problem solved.