It doesn't appear as though Plesk formally supports TLSv1.3. Either that or the sslmng command needs to be updated. How would you enable TLSv1.3 for nginx?
Code:
user@pleskserver:~# plesk sbin sslmng --custom --protocols="TLSv1.2 TLSv1.3"
WARNING:Ignoring unsuppored protocol TLSv1.3
Code:
user@pleskserver:~# plesk -v
Product version: Plesk Onyx 17.5.3 Update #22
Update date: 2017/09/18 06:25
Build date: 2017/03/17 16:00
Code:
user@pleskserver:~# nginx -v
nginx version: nginx/1.11.10