How to catch something that breaks https connection?

Question

HTML

I apologize for the tags, I can not attribute to any section. So, there are several sites on support and their certificate periodically falls off, that is, the site is loaded, loaded on a secure connection and at the last moment the certificate falls off and what did not have time to load from scripts or icons, respectively, is displayed crookedly or not displayed at all. The problem is very rare, I can’t practically catch it, everything is always normal. On the other computer very often occurs. In the console, something like "uploading an image file using the http protocol, so the entire site has been converted to http."

Answer 1

F12 -> Network

Answer 2

Is it stupid to look at the logs in the browser and on the server?

Answer 3

developer console