Can't get DNS to work on a Raspberry Pi cluster

I’m having some trouble setting up Kubernetes with coredns and Flannel, on a cluster of 4x Raspberry Pis. After installing kubeadm on my master node and pulling images, I initialized it with this command:

sudo kubeadm init --token-ttl=0 --pod-network-cidr= --apiserver-advertise-address=

And then I installed Flannel v0.13.0 using this command:

kubectl apply -f

So far, so good. It spawns the Flannel daemonset on all nodes, and I can launch containers. However, unfortunately, DNS does not work on my containers. I check the /etc/resolv.conf file and they all point to, but this doesn’t seem to work. If I kubectl exec into a running pod and from there run dig… it just times out. (Whereas if I run dig @ it immediately returns a result, so at least I have Internet connectivity! And that narrows it down to a cluster DNS problem.)

I was reading that you have to pass --pod-network-cidr= during set up in order for Flannel to work. And as far as I can tell it is working. I’m just wondering if there is an additional parameter I’m missing that will get DNS to finally start working as well?