Help with etcd with IPv6 address

Hi
I am attempting to deploy K8s 1.13 using Kubeadm with HA cluster, stacked etcd and IPv6 address. However, etcd is sending and receiving on v4 address. The /etc/hosts file has only v6 address and its causing etcd cluster to fail. Is there any way to config kubeam to use v6 address for etcd cluster bringup?

Thanks

Song