"Blocked a frame with origin "https://cdn.site.ru" from accessing a frame with origin "https://site.ru". Protocols, domains, and ports must match"?

Question

Ruby on Rails

There is a main domain https://site.ru
There is a subdomain - https://cdn.site.ru , where, thanks to the CNAME record, I mask the original domain.
The original domain works only on the http protocol.

On the page on https://site.ru I insert several iframes with the URL https://cdn.site.ru .

There are a bunch of errors:

Blocked a frame with origin " https://cdn.site.ru " from accessing a frame with origin " https://site.ru ". Protocols, domains, and ports must match.

If I insert the original link into the iframe, and not https://cdn.site.ru , then I get:

[blocked] The page at about:blank was not allowed to display insecure content from https://cdn.site.ru/ ..........

How to fix it? Why YouTube videos work fine and this doesn't?

Answer 1

1. Why produce a question?
2. mod_proxy() - did not help?
3. What headers are coming from the frame page?

Answer 2

Customize Access-Control-Allow-Origin