After having put 1800000 ms I could not connect to freenas anymore !....
Fortunatly I have a cam IP which send me mails if there is an alarm. In the mail I can get my public IP. With my public IP I COULD connect to freenas. After coming back to 1800 ms(???) it was OK after approximatly half an hour. SO may be the parameter is IN SECONDS and not in milliseconds? Who knows?