Why did pictures and styles stop loading completely?

Question

Apache HTTP Server

Yesterday, our web server (Ubuntu/Vesta) crashed early in the morning, when we did a reboot, images and CSS stopped loading completely. This happens randomly, sometimes it will download everything, sometimes partially, sometimes it will only show the text, and sometimes just an error: "ERR_SSL_PROTOCOL_ERROR" . Those images and styles that did not load are displayed in the console like this: "ERR_SSL_PROTOCOL_ERROR /css/app.css Failed to load resource errors" .
I shoveled through all the logs, I did not find any errors. The server was not touched either (only some people worked with the wordpress admin panel and php scripts, in separately allocated directories). I did an update to all services, but it did not help. This glitch is observed even if I open a single .jpg from the server via IP.
Any ideas?
PS at the moment, I restored the backup on a separate machine the day before the "incident", but I'm afraid that the same thing will happen.

Answer 1

Certificates used? Certificate files in place? Not damaged?