I did a ssh tunnel redirecting my server:3689 to localhost:3689, to see if it works better.
Amarok can see my firefly library, and it works better but not perfectly !
Playing the same songs as previously, now between 5 and 15 seconds are skipped at the end.
I followed :
http://wiki.mt-daapd.org/wiki/SSH_Tunnel
and more exactly this : http://nozell.com/blog/2006/11/29/access-a-remote-daap-share-by-tunneling-over-ssh-ubuntuedgy/
for ubuntu (linux)
I do not manage to make Banshee find my library anyway, only Amarok can but still with truncated songs