Issue Very long SSL handshake time

[eronardiaras]

Server operating system version

CentOS Linux 7.9.2009 (Core)

Plesk version and microupdate number

Plesk Obsidian 18.0.46 #2

What can cause it? Where should I look for the error?
All websites (https) load slowly, even the plesk admin interface.


curl -s -w '\nLookup time:\t\t%{time_namelookup}\nConnect time:\t\t%{time_connect}\nSSL handshake time:\t%{time_appconnect}\nPre-Transfer time:\t%{time_pretransfer}\nRedirect time:\t\t%{time_redirect}\nTime to first byte:\t%{time_starttransfer}\n\nTotal time:\t\t%{time_total}\n' -o /dev/null http://mywebpage.com

Lookup time: 0.029
Connect time: 0.029
SSL handshake time: 0.000
Pre-Transfer time: 0.029
Redirect time: 0.000
Time to first byte: 0.029

Total time: 0.029

curl -s -w '\nLookup time:\t\t%{time_namelookup}\nConnect time:\t\t%{time_connect}\nSSL handshake time:\t%{time_appconnect}\nPre-Transfer time:\t%{time_pretransfer}\nRedirect time:\t\t%{time_redirect}\nTime to first byte:\t%{time_starttransfer}\n\nTotal time:\t\t%{time_total}\n' -o /dev/null https://mywebpage.com

Lookup time: 0.029
Connect time: 0.029
SSL handshake time: 1.191
Pre-Transfer time: 1.191
Redirect time: 0.000
Time to first byte: 6.109

Total time: 78.816

 

[eronardiaras]

In the meantime, I realized that "SSL handshake time" might not be the fault. Rather the TTFB and Total time is worrying.

But I still don't know where to look for the error.

I checked this, tried it (and much more...):

https://support.plesk.com/hc/en-us/articles/213940705-Host-s-TTFB-is-too-high-What-can-be-done-to-improve-it-

But there is the problem that the admin interface is very slow, even though it was lightning fast a few days ago. Not to mention the webpages.