I have resolved the problem. It's very weird but in NAS synology sharing the directory with a ip as 192.168.1.* does not work with batocera (but it's working with other systems). I have change the ip to 192.168.1.2 (ip of batocera) and now it's working without problem.
I have read about problems like this (unmatched host on /var/log/messages of synology) and seems to have a relation with ipv6. I don't know but now it's working.
Thanks!