Hello,
Pour le ping il ne se passe pas grand chose :
ping FBPxNAS.lan
PING FBPxNAS.lan (192.168.10.246) 56(84) bytes of data.
^C
--- FBPxNAS.lan ping statistics ---
25 packets transmitted, 0 received, 100% packet loss, time 24573ms
ping FBPxNAS.local
ping: FBPxNAS.local: Nom ou service inconnu
ping FBPxNAS
ping: FBPxNAS: Nom ou service inconnu
mount -t cifs //192.168.10.246/Backup -o guest /media/freebox
mount error(115): Operation now in progress
Refer to the mount.cifs(

manual page (e.g. man mount.cifs) and kernel log messages (dmesg)
a priori le dns est bien gérer. Le firewall peux t il etre bloquant ?