It’s not a matter of browser caching, but server-side caching.
Unfortunately, I can’t test SG Optimizer, because it’s not possible to activate it on a server that is not Siteground.
In any case, until your server serves the same cached version to both mobile and desktop devices, you can’t use this plugin.
I suggest you open a support thread with SG Optimizer and ask them how to serve a different cache (server-side, not browser cache) to mobile devices.
Tell them you have a plugin that creates a different HTML version for the mobile device.
If Divi provides a server-side caching system, be sure it creates a different cache for mobile, or disable the cache of Divi if possible.
In the worst-case SG Optimizer has no options to have a different cache on mobile, you have two options if you want to use SCFM without problems:
– Replace SG Optimizer with a plugin that gives you the possibility to create a different cache for mobile, e.g. W3 Total Cache (free), WP Fastest Cache (premium, the free version doesn’t do it), Powered Cache (free), WPRocket (premium).
– Renounce to the cache for the pages where you have a mobile version.
Unfortunately, you have no other options if you want a different version for mobile.
@doeye