[Samba] Failed to find cifs/foo.bar in keytab MEMORY:cifs_srv_keytab (arcfour-hmac-md5)]

[Eugene M. Zheganin]

Hi.

I'm using Samba 4.3.11 as a domain member on FreeBSD 10.x.

Some of my users (around 1%) are experiencing problems from time to
time, browsing this server's shares in Windows Explorer - it starts to
ask for the password. It doesn't ask the password while accesssing it
via it's IP address, and I see in its logs the following (when accessing
it via its name):

[2016/09/20 10:54:31.451826,  1]
../source3/librpc/crypto/gse.c:497(gse_get_server_auth_token)
  gss_accept_sec_context failed with [ Miscellaneous failure (see text):
Failed to find cifs/wd.norma.com at NORMA.COM(kvno 2) in keytab
MEMORY:cifs_srv_keytab (arcfour-hmac-md5)]

(yup, I know norma.com isn't legitimate, but it's internal domain name).

How can I debug and solve this ?
norma.com is resolving from this machine, so does wd.norma.com. AD
controller shows the cifs/wd.norma.com at NORMA.COM is mapped to the wd
machine (it wasn't, I mapped it by hand, but nothing changed).

I googled this issue a bit, but didn't find any appropriate solution.
I'm not using a dedicated keytab for samba (I tried once, to solve this
issue as was proposed in some article, but it made things even worse).

Thanks.
Eugene.