If you're using a CDN you may want to make sure it's properly configured, especially if you're using pull origin. You can test this by running your page through [
webpagetest.org...] to see if you're getting an F score for "Cache static content". In that instance, you'll see css/js/svg/font/static files being rejected from the CDN and served from your domain instead.
1) Make sure HTTP/2 is activated on your server. For instance, Apache requires you to install the mod_http2 module. You can use the following site to determine if your site's been configured for HTTP/2: [
tools.keycdn.com...]
2) When transitioning to HTTPS you may activate HTTP/2, but the CDN may have an old configuration set to only support versions HTTP/1.1, HTTP/1.0. You'll have to update its settings to accept all three: HTTP/2, HTTP/1.1, HTTP/1.0
3) Check the CDN's origin SSL protocols. It may be set to TLSv1 and SSLv3 when it should probably be set to just TLSv1.2 or at least TLSv1.2, TLSv1.1, and TLSv1
4) Check the CDN's origin protocol policy (how the CDN should connect to your site) to make sure it's not set to only HTTP. It should either be set to HTTPS or match protocol.
5) Make sure your CDN whitelists the "origin" header, otherwise your static files may not be cached according to the settings established by your server. For instance, if your site is setup to instruct browsers to cache CSS or JS files for an extended period of times (e.g., months, one year) and your CDN is set to reject your response headers, none of your caching rules will take effect which means your visitors aren't getting an optimum cache experience. Some CDNs will reject any headers you send for optimization purposes unless you instruct otherwise.
6) Make sure you're starting with a small HSTS setting of around 5 minutes and increment upward over time once things are looking good. The following website will test your site for HSTS and provide recommendations on how to increment it over time:
[
hstspreload.org...]
7) Take a look at HTML5 Boilerplate Server Configs for how to optimize your server, especially for SSL and HTTPS: [
github.com...]
8) If you're using WordPress Yoast SEO plugin, you may want to check your sitemap to make sure the links are pointing to the "https://" links. If not, deactivate just the sitemap setting (not the entire plugin) then reactivate to fix.
9) When you're done, run your site through both [
webpagetest.org...] and [
ssllabs.com...] to make sure nothing is awry.
10) This should be obvious and previously mentioned, but make sure your 301 HTTP to HTTPS redirects are in place.