first disable systemd-resolved service.

systemctl disable systemd-resolved.service

Stop the service

systemctl stop systemd-resolved.service

Then, remove the link to /run/systemd/resolve/stub-resolv.conf in /etc/resolv.conf

rm /etc/resolv.conf

Add a manually created resolv.conf in /etc/

nano /etc/resolv.conf

Add your prefered DNS server there

nameserver 8.8.8.8