If you start running into mysterious CIFS mount errors on a recent Debian (“mount error(95): Operation not supported“) or autofs stops working (“mount(generic): failed to mount //192.168.178.2/YY (type cifs) on /home/YYY”),
try to add “vers=2.0” (or vers=1.0) to your mount options. Recent kernels default to samba version 3, which apparently is not supported by many boxes (including my Synology)