samba - Nov 2019 - Subject=Re: Mac Clients Disconnect with: source3/smbd/service.c:1050(close_cnum) closed connection to service data

Dear Todd,

Thanks for all of the suggestions, yes testparm comes back fine. It used to
complain but, Rowlands original suggestion silenced the complaints, except
for one:
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384)

But that's been around for years before the issue at hand.

Wilfred Smith's Wireshark suggestion on Stack Exchange eventually took the
focus away from Samba, Ubuntu and Apple, and had me log into the Windows
Server 2016 domain controllers. The DC assigned with the Primary Domain
Controller role had a much higher uptime than it ever should have, and it
also was at a steadily higher CPU usage than the others. I transferred the
PDC role to another DC in the trio, and restarted the one with the high
uptime. Since doing so at around 7 am on October 31st, the problem seems to
have gone away.

I am hoping this is the solution even if it leaves a lot of open questions.
If it is the solution I think the lesson is to let the domain controllers
cycle regularly.

I'll let you know how it goes.

All the best,
Louis