LetsEncrypt on 10.5 not working

I am running 10.5 on Google Cloud Platform. Ports 80 and 443 are open to I have verified that the instance is reachable via multiple networks on the Internet. However, when I set letsencrypt[‘enable’] = true and run gitlab-ctl reconfigure, the SSL certificate is for www.example.com rather than the domain external_url is set to.