Thank you for the post.
If using SSL, then the recommendation would be to install the latest security update.
“Use Secure Sockets Layer (SSL) to encrypt data passed between FileMaker Server components and FileMaker Pro, Go, and WebDirect clients. Progressive downloading allows clients to use interactive content as it is being downloaded. Progressive downloading uses unencrypted HTTP connections, even if the Require secure connections setting is enabled. Restart Database Server to apply a change to these settings.
Warning: The standard FileMaker SSL certificate installed by default on this server is available for test purposes only.
A custom SSL certificate is required for production use. Obtain a custom SSL certificate from a Certificate Authority (CA) supported by FileMaker.”
Thank you, TSFalcon.