[Samba] Connection time-out opening documents since system update and reboot

[Daniel Botting]

Dear Sirs,

Yesterday after an update of our office file server (apt packages and 
then a reboot) most documents time-out when they are opened, host 
specifics below:

Distribution        :    Debian 9.9

Samba version   :    4.5.16-Debian

syslog:

Jun 20 10:09:26 hostname smbd[19246]: [2019/06/20 10:09:26.216093,  0] 
../source3/smbd/process.c:2860(keepalive_fn)
Jun 20 10:09:26 hostname smbd[19246]:   send_keepalive failed for client 
ipv4:<internal range ip address>:50324. Error Broken pipe - exiting

smbd.log (is repeated on multiple occasions)

pid_to_procid: messaging_dgm_get_unique failed: No such file or directory

Please advise if you have seen this issue before and possible steps to 
resolve.

Many thanks

Daniel