Secure connection required error when server returns 200

Recently makeWebRequest has started returning a -1001 response status. This is after the request gets to the server, the PHP script writes the URL encoded values into a database, and the nginx server returns 200 as the response code per the log. The SSL certificate doesn't expire until July. This is with SDK 7.1.1 and a Fenix 7x with CIQ 5.0.0. What's changed, and what's the workaround?