Tried the DEBUG option but dumpdebugbuffer doesn't show anything about smbfs (do I need kernel.debug loaded too???)
NETBIOS option/switch tried too and get error on loading/launching smbfs V1.102:
#samba:bin/SMBFS workgroup=GRUPO user=*** password=*** service=//WDRED/PUBLIC DEVICE=SMBFS0: VOLUME=WDRED TRANSLATE=L:FileSystem_Trans/INTL.crossdos NETBIOS
SMBFS: Cannot connect to server (5, Input/output error).
SMBFS: Could not connect to server (5, Input/output error).
(BTW although error is different [5 vs 61] with/without NETBIOS switch)
Seems I have to stick with smbfs V1.74 with my old WD-NAS
THX @all for helping