I have a root domain (https://kernl.us) that is secured via a Let's Encrypt SSL certificate. This works fine, but when I try to go to a new sub-domain (http://status.kernl.us) Chrome redirects me to HTTPS. The sub-domain is a CNAME record that points to a Pingdom status page. I have no control over it's HTTP/S status.
If I open Firefox there is no HTTPS redirect. I suspect that this has to do with the Let's Encrypt SSL cert and some stored behavior in Chrome, but I'm not sure where to start looking.
I found this: https://community.letsencrypt.org/t/every-subdomain-is-redirecting-to-https-even-non-existent-ones/18095 which seems to be my problem, but my Nginx config isn't setting any