Downlink not received on Lora CLASS C about lorawan-server HOT 2 OPEN

Hello,
I have the same kind of problem using curl in a php script. When the json include the "time" parameter, server return a 500 error code but returns 204 "no content" for the same json without "time".
However, the same request sent in a terminal windows works well. for example :
curl -v --digest -u admin:admin -H "Content-Type: application/json" -X POST http://192.168.1.2:8080/downlink -d "{"deveui":"70B3D53260ABCDEF", "data":"0A0078", "port":13, "time":"immediately"}"

from lorawan-server.

I found port parameter must be an integer within the json :
{"deveui":"70B3D53260ABCDEF", "data":"0A0078", "port":13, "time":"immediately"} => OK.
{"deveui":"70B3D53260ABCDEF", "data":"0A0078", "port":"13", "time":"immediately"} => KO.
but {"deveui":"70B3D53260ABCDEF", "data":"0A0078", "port":"13"} is working anyway.

from lorawan-server.