TN3179:

During testing, you might want to reset your program’s Local Network privilege to the undetermined state. Your options for this vary by platform.

On iOS, the easiest option is to delete your app.

Alternatively, if you don’t want to delete your app for some reason, reset the entire privacy subsystem using Settings > General > Transfer or Reset > Reset > Reset Location & Privacy.

On macOS, the list in System Settings > Privacy & Security > Local Network has add (+) and remove (-) buttons. To reset your program’s Local Network privilege, select it in the list and click the remove button.

Source: Michael Tsai - Blog - Resetting Local Network Privacy

We are in the early innings of personal software and so I suspect things like this and other Settings are going to go through a wild ride of design changes until we find a new normal.