My client has same issue - Hosted at iPage. Started in November/December. Auto Post Notifications not going out.
Using Mailpoet. No previous issue. Checking with plugin WP Crontrol. (Tools/Cron Events) Error message appears
"While trying to spawn a call to the WP-Cron system, the following error occurred:
cURL error 35: gnutls_handshake() failed: A TLS packet with unexpected length was received."
Talking to their support - very nice and hopefully fixed today as per their customer service. If not, discussed moving website to a different server. I have other clients with iPage, using Mailpoet and no issues/no cURL errors.
Don't know if this would help but customer support said yes. Makes sense but what does that got to do with anything. lol!