I've faced the exactly same problem but I've fixed it with another approache.
Using Ubuntu 18.04, first disable systemd-resolved
service.
sudo systemctl disable systemd-resolved.service
Stop the service
sudo systemctl stop systemd-resolved.service
Then, remove the link to /run/systemd/resolve/stub-resolv.conf
in /etc/resolv.conf
sudo rm /etc/resolv.conf
Add a manually created resolv.conf
in /etc/
sudo vim /etc/resolv.conf
Add your prefered DNS server there
nameserver 208.67.222.222
I've tested this with success.