[Samba] Strange problem with winbind on linux domain member (works for 2 minutes...)

[Jakob Curdes]

Hello, after upgrading a samba4 AD domain member server on ubuntu24 
(Re-joined with same name, but probably unrelated), I expreience a 
strange behavior.

When starting all three services smbd,nmbd,winbind, everything works. 
Then after about 2 minutes, the shares are not accessible any more, and 
winbind shows an error message on systemctl status:

Feb 05 13:35:01 *** winbindd[3131]: [2026/02/05 13:35:01.392619, 0] 
source3/winbindd/winbindd_samr.c:71(open_internal_samr_conn)
Feb 05 13:35:01 *** winbindd[3131]:   open_internal_samr_conn: Could not 
connect to samr pipe: NT_STATUS_CONNECTION_DISCONNECTED

I first had the time sync as idea, but the server is in sync with DC and 
the workstations which are also domain members.
Time zone is also the same.
Other than this error I find no clues. All wbinfo tests succeed, 
kerberos is fine, etc.

Probably relevant part of smb.conf (but this config is exactly the same 
as before the upgrade):

    winbind refresh tickets = Yes
    dedicated keytab file = /etc/krb5.keytab
    kerberos method = secrets and keytab
    winbind use default domain = no
    winbind enum users = yes
    winbind enum groups = yes
    winbind nested groups   = Yes
    winbind expand groups   = 4

Any idea what could cause this? The DCs are also Ubuntu 24. We have no 
other known issues in the domain, but this actually the only LINUX 
member server.
I now restart winbind every minute via cron, but this is obviously a 
workaround....

Best regards, Jakob