[Samba] Intermittent permission denied when accessing share

[Lorenzo Milesi]

I'm having a weird situation with a freshly installed Samba v4.12.1 compiled from source. This is a single server with DC and fileserver, I followed all the guidelines for doing things correctly in this specific situation and I hope I haven't missed anything.
The server works correctly as expected, I'm managing all the permissions from Windows. 
Unfortunately users occasionally experience problems in accessing some shares they used to. This happened three times, so far only to two different shares. When the event occur all computers in the domain are unable to access the share, and I'm able to restore functionality by just restarting samba-ad-dc.service. I tried "reload-config" but won't work. After restarting the service everything is back to normal. The first time this happened I had to restart again within 4h, then it didn't happen again for days. 

Last time it has been reported to me today, I tried accessing "RESPONSABILI" share few minutes after 16:00 from PC 10.0.0.197 (myuser at CM-WM-W7) and access was prohibited. Restarted around 16:06 and access was restored. 
As this happened before I raised log level to 8 and I now have debug logs.

One note: I read in the logs several NT_STATUS_NO_SUCH_USER errors from the above client. Before this Samba server we had a Samba4 installation in workgroup mode, these auths seems to be mapped to the OLD workgroup name, and I suspect these are from Windows' background services trying to authenticate to the old server. 

Thanks

** smb.conf
# Global parameters
[global]
        netbios name = FILESERVER
        realm = WDC.MYDOMAIN.IT
        server role = active directory domain controller
        server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc, drepl, winbindd, ntp_signd, kcc, dnsupdate
        workgroup = WDC
        netbios aliases = server3
        idmap_ldb:use rfc2307 = yes
        template homedir = /home/%U
        hide unreadable = yes
        # temporary requirements for 2 xp clients 
        server min protocol = NT1
        client min protocol = NT1
        log level = 8
[sysvol]
        path = /usr/local/samba/var/locks/sysvol
        read only = No
        browseable = No
[netlogon]
        path = /usr/local/samba/var/locks/sysvol/wdc.mydomain.it/scripts
        read only = No
        browseable = No
[homes]
        path = /home/CONDIVISI/personali
        include = /usr/local/samba/etc/cestino.conf
        read only = No
[RESPONSABILI]
        path = /home/CONDIVISI/RESPONSABILI
        read only = No
        include = /usr/local/samba/etc/cestino.conf

** cestino.conf:
        vfs objects = dfs_samba4 acl_xattr recycle
        recycle:repository = .cestino/%U
        recycle:keeptree = yes
        recycle:touch = yes
        recycle:versions= yes
        recycle:exclude = *.tmp *.bak ~$*
        recycle:exclude_dir = /tmp /temp /cache
        recycle:noversions = *.doc *.xls *.ppt
        recycle:directory_mode = 770
        recycle:touch_mtime = yes


LOG FILES: as I couldn't find the policy for this ML I didn't dare posting 4MB of files in a single message, so they're available on the two links below. If it's not a problem I'll paste them to a new mail in this thread.
https://cloud.ufficyo.com/nc/s/XaSG8GGDFwgPpHf
https://cloud.ufficyo.com/nc/s/jbwFnDDJ7mQnPQM

-- 
Lorenzo Milesi - lorenzo.milesi at yetopen.it

YetOpen S.r.l. - https://www.yetopen.it/
Via Salerno 18 - 23900 Lecco - ITALY -
Tel +39 0341 220 205 - Fax +39 178 6070 222

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