After installation, the package may be configured at Services > NUT.
The package does not have a lot of input validation in the GUI. If NUT
will not start after configuration, check the System log (Status >
System Logs) for log entries starting with
nut:. The culprit is likely
explained there, such as selecting a cable for a driver type that does
not need (nor permit) the cable selection.
If the system log doesn’t offer adequate information, such as simply logging:
nut: Service failed to start: check configuration
Log in via SSH and choose option
8, then run the following command:
Configuration errors will be displayed in the output if any are found.
You can find a list of known issues with the NUT package on the pfSense bug tracker.