I am getting the following error on the frontend of my Magento 2 (v 2.2.3) website when trying to share Wishlists or send a Contact Form. This hasn't always been the case just since I switched from PHP 5.6 to 7.0.14;
Warning: stream_socket_enable_crypto(): Peer certificate CN='xxx.com.au' did not match expected CN=`localhost' in public_html/vendor/magento/zendframework1/library/Zend/Mail/Protocol/Smtp.php on line 206
I have a valid (and tested) SSL certificate installed. So, it is not an issue as per other posts of the SSL certificate not being valid.
I have also disabled SMTP Restrictions in my WHM settings (as per another post) and this doesn't work either.