Zoho Rejects SMTP connection from our server

Zoho Rejects SMTP connection from our server

Dears,

We had some troubles trying to send emails from our website through SMTP with Zoho.
When debugging, it results in a rejection from Zoho to establish connection.
So since the 3-5 days ago we've been unable to send emails.

What may be causing the underlying problem?
Attached: TLS and SSL protocol debug.

Thank you very much!

Sven