Long loading site. SSL Initial connection is very large. What to do?

Question

Apache HTTP Server

Hello!
There are VDS on Apache/2.4.29 and Ubuntu 18.04. It runs about 30 sites (The load is not very large, rarely exceeds 70% CPU usage). Sometimes the site starts to load very slowly. The Network tab shows that the download and setup of the connection associated with the SSL certificate takes the longest. All sites have Let's Enctypt installed. This situation is not repeated often and is periodic.
Please tell me what can be done here? I will be glad to any advice. Thank you.

Answer 1

Initial connection 17c is purely server, it hangs stupidly. Turn on the site simply without ssl, it will probably respond with the same delays at these moments. Dig further into server logs, settings, etc.
The SSL verification service of the site https://www.ssllabs.com/ssltest/
is there if there are any recommendations on the incorrectness of certificates, but this should affect the TTFB time more.