ERROR: Status code is 0

Hello,

Recently the plugin has stopped working on the website.

Here are images to the errors we are receiving.

View post on imgur.com

View post on imgur.com

Please advise on how to fix this.

Thanks,
Justin

******
Diagnostic Test

Mailer: postsmtp
HostName: csrslearn.co.za
cURL Version: 7.64.0
OpenSSL Version: OpenSSL/1.0.2r
OS: Windows NT COM035_TRUSERVP 10.0 build 17763 (Windows Server 2016) i586
PHP: WINNT 7.1.29 English_South Africa.1252
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=No, allow_url_fopen=Yes, mcrypt=Yes, zlib_encode=Yes
WordPress: 5.6.1 en_US UTF-8
WordPress Theme: Course Builder
WordPress Plugins: Add From Server, Akismet Anti-Spam, Anywhere Elementor, bbPress, Better Notifications for WP, Caldera Forms, Contact Form 7, Design Upgrade for LearnDash, Elementor, Flexible Checkout Fields, WPBakery Page Builder, HubSpot All-In-One Marketing - Forms, Popups, Live Chat, LearnDash LMS - Course Grid, LearnDash LMS - Notifications, LearnDash ProPanel, LoginPress - Customizing the WordPress Login, MC4WP: Mailchimp for WordPress, Peter's Login Redirect, Post SMTP, Post/Page specific custom CSS, Slider Revolution, LearnDash LMS, Thim Core, Thim Course Builder, Thim Portfolio, Under Construction, UpdraftPlus - Backup/Restore, Increase Maximum Upload File Size, User Menus, User Registration, Widget Logic, WooCommerce PayPal Checkout Gateway, WooCommerce, WordPress Social Login, WP Events Manager - WooCommerce Payment Methods Integration, WP Events Manager, WordPress REST API Authentication, WPS Hide Login
WordPress wp_mail Owner: C:\inetpub\CSRSLearn\wp-content\plugins\post-smtp\Postman\PostmanWpMailBinder.php
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email, bbp_mail, PostsmtpMailer->get_mail_args
WordPress phpmailer_init Action(s): wpcf7_phpmailer_init
Postman: 2.0.21
Postman Sender Domain (Envelope|Message): csrs.co.za | csrs.co.za
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SendGrid API (https://api.sendgrid.com:443)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 15473 | 15468
Postman File Locking (Enabled|Temp Dir): No | /tmp

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