HTTP API service

Trying to get the HTTP API service running, but falling at the first hurdle.

Excerpt from my config

https {
    api {
        keys {
            id api-key {
                key 6d6c4a50
            }
        }
        port 56345
    }
}

When trying to test from a computer using the following command I get a connection refused error.

curl -k -X POST -F data='{"op": "showConfig", "path": ["interfaces", "dummy"]}' -F key=6d6c4a50 https://192.168.68.1:56345/retrieve

I have a ZB firewall config, the rules for lan-local and local-lan are set to default accept.

Any help would be much obliged.