OCP 3.1 install fails on TASK: [etcd | Enable etcd]

Issue

After completing all the pre-requisites for 3.1 mentioned in the documentation, the ansible installer failed on task:

TASK: [etcd | Enable etcd] ****************************************************
failed: [node_name] => {"failed": true}
msg: Job for etcd.service failed because a timeout was exceeded. See "systemctl status etcd.service" and "journalctl -xe" for details.


FATAL: all hosts have already failed -- aborting