Once you’ve worked out how your website can detect HTTPS, you may be able to make it the fix permanent without the need for this plugin.
NB: developers only; don’t try this at home if you’re not already comfortable editing PHP!
If your website can already detect HTTPS, then there’s nothing to do. If it can’t detect HTTPS, then you should consider switching your website entirely to HTTPS with no HTTP access, or keep running this plugin with “unable to detect HTTPS” selected.
If your website is running with one of the other choices, then look at the
proxyFix() method in the SSLInsecureContentFixer class to see how it is detecting HTTPS for your selected method. You can copy that code into your
wp-config.php file, and it will work when you deactivate this plugin.
Remember to keep a copy of your old
wp-config.php somewhere safe in case your break your website!