I have been able to get a demo of it working on my own webserver over here: ad banners - so I know that it can work, it just isn’t working in the header or footer of my Discourse
I found this discussion: Supporting iframe embeds from different domains? - so I tried to add the subdirectory and script (banner.html) to the whitelist.
The iframe seems to embed in the page, but it does not display any of the images listed in array in the leaderboard.js
Is there anything else I can try? Or do is this only possible on my own hosted server?