k3d failed to pull image "docker.io/rancher/pause:3.1"
I had the same issue with k3s not being able to pull images and solved it by updating my /etc/resolv.conf to be symlinked from /run/systemd/resolve/stub-resolv.conf on the host machine with
ln -sf /etc/resolv.conf /run/systemd/resolve/stub-resolv.conf