Ok I begin to understand how to fill loraserver.toml 
it’s my luck
I wrote the result of openssl rand -base64 32 command in network_server.gateway.api.jwt_secret ok I’m glad then when I start loraserver and that I check it ( sudo systemctl start loraserver & journalctl -u loraserver)
“class-c scheduler error” what is this ?!?:
I found an indical pb ==> https://forum.loraserver.io/t/loraserver-gave-pq-syntax-error/855
Probably that I need to follow the instrction…