If your network configuration requires using TLS (Transport Layer Security) encryption for communication with the Flow Server, this can be enabled by locating/creating a "bootstrap.settings" file and adding the following to the file.
See the article How do I change the default port that Flow components use to communicate with each other? for more information on the bootstrap.settings file.
If you've already changed the default port, as per that article, then you will need to include port properties in the bootstrap.settings file. For example: