I want to use iframe tag in html page with the base of webconfig. If I use the URL of my website itself in the SRC of the iframe, it works well, but if I use another link like even the url of W3scool, It faces this error Content Security Policy of your site blocks some resources.

Here is how I used this code

and my website is just pure html css javascript without any especial backend but based on Webconfig.

I really appreciate if some one could help me on this issue. With Appreciation and Respect