Cansin Acarer

This happens if the internet connection is shown as “unmanaged“. So you need to edit this file to make it “managed“:

sudo nano /etc/NetworkManager/NetworkManager.conf

Change managed=false to true. Then restart the network-manager:

sudo service network-manager restart

Make sure network is managed by network-manager:

sudo sed -i '/^network:/a \    renderer: NetworkManager' /etc/netplan/50-cloud-init.yaml

Apply changes

sudo netplan apply

Then reboot.