Sites not caching on Pantheon hosting with CDN

I’ve been trying to solve this problem for sometime and it took a ridiculous amount of time to realize that WP Cerber was setting cookies because they are created using random characters for both the name and the content. (the first red flag).

Once I narrowed that down, I tried adding STYXKEY_ as a prefix thinking mistakenly that would tell the CDN to ignore the cookies but as other users found ANY cookies that aren’t explicitly excluded from the CDN (like google analytics) make the cache fail because it is expecting that cookies are being used to provide different content.

I was finally able to resolve this (fingers crossed) because of this answer here:

There is no way we (SiteGround) can ignore cookie session and cache such pages. Basically, you are disabling our caching mechanism on all pages. Opening a cookie session for anything but to display user-speciffic content is a bad idea really.

WP Cerber does not use its cookies as session identifiers or anything specific to a user. Cookies are just cookies and they are used for many reasons not related to sessions.

So, to make WP Cerber compatible with Siteground’s caching system, you need to disable
“Protect comment form with bot detection engine” and “Protect all forms on the website with bot detection engine” in the anti-spam settings.

I disabled all the anti-spam settings, cleared the cache, reloaded the page a few times, and was finally able to get cache HIT.