samba - Nov 2023 - windows workstations needing reboot to validate passwords.

I am (earlier reported under the subject "Peculiar Problem") having an
issue that started several weeks ago, where windows (10 pro, server
2019) computers randomly get into a state where they refuse to validate
passwords. Rebooting (sometimes several times) makes the problem go
away. You can also log in if you disconnect the PC from the network and
then reconnect.

List of changes around the time it started.

Samba upgrade to 4.19.2
Samba schema upgrade to 2012_R2 functional level?
Samba upgrade to 2008 functional level

List of measures taken (hoping that if best practises are not being
observed, implementing them will fix things!!)

Moved DNS from SAMBA_INTERNAL to BIND_DLZ
Moved ntp from ntpsec to chrony

Diagnostic steps

Packet dumps (decoded with keytab) and loglevel 255 show no glaring
issues or errors.

Going to try restarting all of the DC's next time it happens to
determine if the miscommunication originates with windows or samba.


Any other suggestions welcome!!