onnection failed. Error #2: stream_socket_enable_crypto()

Hello,

This is the Error Summary:

Versions:
WordPress: 5.9.1
WordPress MS: No
PHP: 7.4.28
WP Mail SMTP: 3.3.0

Params:
Mailer: smtp
Constants: No
ErrorInfo: SMTP Error: Could not connect to SMTP host.
Host: smtp.tszdelmenhorst.de
Port: 587
SMTPSecure: tls
SMTPAutoTLS: bool(true)
SMTPAuth: bool(true)

Server:
OpenSSL: OpenSSL 1.1.1 11 Sep 2018

Debug:
Email Source: WP Hide & Security Enhancer
Mailer: Benutzerdefinierter SMTP-Server
SMTP Error: Could not connect to SMTP host.
Email Source: Wordfence Security
Mailer: Benutzerdefinierter SMTP-Server
SMTP Error: Could not connect to SMTP host.
Email Source: WP-Kern
Mailer: Benutzerdefinierter SMTP-Server
SMTP Error: Could not connect to SMTP host.
Email Source: WP Mail SMTP
Mailer: Benutzerdefinierter SMTP-Server
SMTP Error: Could not connect to SMTP host.

SMTP Debug:
2022-03-10 10:12:26 Connection: opening to smtp.tszdelmenhorst.de:587, timeout=300, options=array()

2022-03-10 10:12:26 Connection: opened
2022-03-10 10:12:28 SERVER -> CLIENT: 220 h2847083.tszdelmenhorst.de ESMTP Postfix (Ubuntu)
2022-03-10 10:12:28 CLIENT -> SERVER: EHLO www.tszdelmenhorst.de
2022-03-10 10:12:28 SERVER -> CLIENT: 250-h2847083.tszdelmenhorst.de250-PIPELINING250-SIZE 20480000250-ETRN250-STARTTLS250-ENHANCEDSTATUSCODES250-8BITMIME250-DSN250 CHUNKING
2022-03-10 10:12:28 CLIENT -> SERVER: STARTTLS
2022-03-10 10:12:28 SERVER -> CLIENT: 220 2.0.0 Ready to start TLS
2022-03-10 10:12:28 Connection failed. Error #2: stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error messages:error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed [/var/www/vhosts/tszdelmenhorst.de/httpdocs/wp-includes/PHPMailer/SMTP.php line 467]
SMTP Error: Could not connect to SMTP host.
2022-03-10 10:12:28 CLIENT -> SERVER: QUIT
2022-03-10 10:12:28
2022-03-10 10:12:28
2022-03-10 10:12:28 Connection: closed
SMTP Error: Could not connect to SMTP host.

Question:

1. where does the information for OpenSSL 1.1.1 11 Sep 2018 come from, because currently only OpenSSL 1.1.1m from 14 Dec 2021 is installed?
2. Currently, I can’t find a solution to the above problem, so I’m wondering if the incorrect OpenSSL version specification is a contributing factor?

The page I need help with: [log in to see the link]