cron ping – ssl error

Hi,

1. The version of the plugin: 3.0.56
2. Your browser and operating system: chrome on windows
3. Address of the page with the problem: here
4. Screenshot or even videos: /
5. Description :

My website is hosted on a dedicated server so I can control everything on it.
I’ve switched to MailPoet because I couldn’t make the Mailgun config work.
But then I realized that the error (which is apparently not detected because it tells “connection successful” under help > system status link) is inside the ping URL.. You can click it here

I don’t know anything of the error. My website just works fine in HTTPS, so what is the deal ?

Thanks

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