Document Write Called After Page Load

I am trying to auto insert an ad block after content, I actually select “footer” from dropdown.

I have Device selection, but when I choose Client Side, I get the errors like this:

“document.write called after page load”

And the ad can’t load.

I seem to have more success with server side detection, but my fear is that the detection will be cached by Cloudflare. So if detection is made that the user is mobile and loads the page that way with the ad set for mobile, Cloudflare will cache that page with the ad for mobile.

Or do I not need to worry about cacheing? If that is the case, server side works. But would prefer to use client side, but the Document.Write error happens immediately upon activating that.

Cheers!
Ryan

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