According to the official list of supported SSL certificates for FileMaker we are recommending QuickSSL Premium to our customers for use with FileMaker (Pro).
Please find CSR creation and installation instructions for FileMaker here:
Attention FileMaker 19 has a bug and might only use the default SSL instead of custom imported SSL. You can find the solution here:
In case FileMaker 19 continues to deliver the default certificate from Claris, you may need to delete the HTTPServer/conf/server.key and server.pem files that hold the default ssl, and then restart the server.
Set hostname for Filemaker server:
scutil --set HostName sub.domain.com
On macOS you might need to also change the computer name, see https://support.apple.com/en-euro/guide/mac-help/mchlp2322/mac