In Apache web server when you add X-Forwarded-SSL request header at Apache web server level, sometimes it adds the header name to the Vary response header. This breaks CDN caching for Akamai and other CDN providers.
The solution is to put a "no vary" flag on the mod_rewrite rules in the conf file that is checking the X-Forwarded-SSL header.
Copy of Apache HTTP Server documentation for this setting:
‘novary|NV’ (no vary): If a HTTP header is used in the condition, this flag prevents this header from being added to the Vary header of the response.
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