just got off a 1.5 hour support call over this issue where if you try to publish or full edit a page or post of a certain length and content (basically a long page of links) you get 502 errored by the server. The final response i was given is "Either switch to regular shard hosting or break up your content into multiple pages"
This seems like a complete rejection of responsibility for an error in the functionality of this spam filter or whatever it is that it cannot recognize a logged in admin user from and external visitor.
If anyone has anything to add to that or an actual solution i'd love to hear it.
I would recommend enabling debug mode in wordpress to try and get an error which indicates the exact problem. Once you have this you should be able to implement a fix as long as it is configuration related and there are no other issues with the site.
Add the define statement to your wp-config.php file and this will enable the log file to be created in /wp-content directory.
WP_DEBUG_LOG is a companion to WP_DEBUG that causes all errors to also be saved to a debug.log log file inside the /wp-content/ directory. This is useful if you want to review all notices later or need to view notices generated off-screen (e.g. during an AJAXrequest or wp-cron run). Note that this allows you to write to /wp-content/debug.log using PHP's built in error_log() function, which can be useful for instance when debugging AJAX events. define( 'WP_DEBUG_LOG', true );
(DO NOT LEAVE IT ON AS IT WILL CAUSE ISSUES IF THE LOG FILE GROWS EXPONENTIALLY)