YES !
So, i have “failed to connect to” because the NAS can’t be connect the FOG server’s mysql.
[U]I explain my work[/U]:
[U]I do on my NAS[/U]:
[B]mysql -h 192.168.56.102 (IP_FOG) -u root -proot fog[/B]
[U]Result[/U]:
[B]Can’t connect to MySQL server on ‘192.168.56.102’ (111)[/B]
Hum. So, maybe i use a bad user for a remote connection. I see the user on mysql server, on the database “mysql”.
[U]On my server FOG[/U]:
[U]Result[/U]:
[IMG]http://image.noelshack.com/fichiers/2015/12/1426779602-mysql.png[/IMG]
Yes. So, i decide to use “fogstorage” because with him, i can use all the host of my network.
[U]I do on my NAS[/U]:
[B]mysql -h 192.168.56.102 -u fogstorage -p[/B]
[U]Result[/U]:
[B]Can’t connect to MySQL server on ‘192.168.56.102’ (111)[/B]
Sh*t, doesn’t work !
I look on my server fog if 3306 is open with [B]netstat -nat[/B] and yes, it’is open.
I look the file /etc/mysql/my.cnf and for the line “[B]bind-address” [/B]i have:[B] 127.0.0.1[/B]. I change for IP_FOG (192.168.56.102), i restart the service.
[U]I do on my NAS[/U]:
[B]mysql -h 192.168.56.102 -u fogstorage -p[/B]
[U]Result[/U]:
mysql>
YOuhouuuu !!! 
I look the fog’s management:
[IMG]http://image.noelshack.com/fichiers/2015/12/1426780354-nas-ok.png[/IMG]
It works ! 
Thank for your help wolbanne8653 !
Sorry for my bad english, I tried to explain precisely what I did, if others have the same problem, they can solve it now.