SMB1 mounts are not supported
Trying to mount a Synology NAS, I get this error:
mount error(95): Not supported
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg)
Can't access remote filesystem
root@omnia:~# dmesg
...
[ 5686.349245] No dialect specified on mount. Default has changed to a more secure dialect, SMB2.1 or later (e.g. SMB3), from CIFS (SMB1). To use the less secure SMB1 dialect to access old servers which do not support SMB3 (or SMB2.1) specify vers=1.0 on mount.
Adding -o vers=1.0
to the mount.cifs command fixes this issue for me. I think the defaults are correct now, maybe adding an option (with a warning) to use the 1.0 version or documenting this would make life easier for some people. If this is the default behavior of some (?) older (?) Synology NASes, this issue would be common.
Either way, I think this message in dmesg is logged even when the server supports SMB3, so it should probably be silenced with -o vers=default
.