I am on a shared host (Apache) and am receiving little help resolving this issue. I have a main domain https://www.waldorfteacherresources.com and I have set up two cookieless domains: static.waldorfteacherresources.com and static.mseifert.com. When loading, Firefox shows many of the static files with a 421 response. Occasionally, the main site's index.php comes back with a 421 error - which then gets displayed in the browser directly. Each time when loading a url, the files with 421 errors can vary. Sometimes I get no 421 responses.
Also odd is that even with files having a 421 response, they seem to load anyway: the
css files are getting loaded (otherwise the site would not render correctly) and the
I am using Comodo SSL and have PositiveSSL Multi-Domain Certificate. The response I get from my ISP is
After reviewing this it looks like the main issue is your sites code is working in a way that is confusing the server.
It appears for some reason the site is making a request to itself and presenting the host header as www.waldorfteacherresources.com while it is actually going to static.waldorfteacherresources.com.
I have read the discussion on 421 Errors here but this isn't helping me figure out if it is somehow my code creating the problem or if there is something on the ISP end that can be changed (of if I need to find a new ISP). Since it is a shared host, they are not going to change the server configuration.
Below are Firefox's network tab for two loads of the same URL. Any help would be appreciated.
I set about getting separate certificates for each domain. I am on a shared host (Webhostinghub) and discovered they now offer free SSL (AutoSSL) that auto renews. It sounded to good to be true. They set me up with 6 free certificates. So far so good. I may even try to re-enable the static domains to test. If this all works, I'll save $ to boot as a bonus and let my Comodo certificates expire in July.