[Samba] Windows clients keep losing connections (FQDN and hostname)

[Zendal Darkman]

Connecting to \\server.domain.xx.uk\share
and \\server\share, works but we tend to lose "\\server\share" within a few
days, *but starts working again*.
\\FQDN\share eventually stops, with windows reporting "network path not
found". If I do a "net use" I can see several connections to \\fqdn\share,
and running "net use * /delete", brings back  the the ability to connect to
\\fqdn\share.

windows machines experience this at different stages. So one machine may
lose connection,but another keeps working.

I should add that if I use  \\<IP>\share, it work's but I don't know yet if
that will  keeps dropping.

HOWEVER, the most important thing is there are some odd firewall rules
between workstations /samba servers, and the rest of organisations servers
including servers such as DNS, domain controllers. The rules allow a
vanilla samba "net join" (although we cant do a DNS update: DNS is
hardcoded on the DNS servers and correct) . All works but for the
occasional drop of connections.

I'm thinking "wins".Like many others before me wonder why ping <fqdn> give
the correct IP, but \\fqdn\ does not work when \\<ip> does. I'm not
familiar with wins. I was thinking wins is not used for fqdn.

My smb is below anything marked with ### is a comment I have put into this
email (not present in actual smb.conf)

[global]
security = ADS
workgroup = domain ###Is this needed?
realm = domain.xx.uk

log file = /var/log/samba/%m.log
log level = 4

min protocol = smb2   ####possible cause of issue?
smb encrypt = mandatory

local master = no
domain master = no
preferred master = no
wins support = no
wins proxy = no
dns proxy = no

dedicated keytab file = /etc/krb5.keytab
kerberos method = secrets and keytab

idmap config * : backend = tdb
idmap config * : range = 3000-7999
idmap config xx : backend = rid
idmap config xx : range = 10000-5999999
winbind refresh tickets = yes

template shell = /bin/false
template homedir = /home/%U

#username map = /etc/samba/user.map

vfs objects = full_audit acl_xattr

full_audit:prefix = %u|%I|%m|%S
full_audit:success = connect disconnect opendir mkdir rmdir closedir open
close read write rename unlink
full_audit:failure = connect
full_audit:facility = local5
full_audit:priority = NOTICE

map acl inherit = yes
store dos attributes = yes

[Audit]
path = /audit
read only = no

[Desktops]
path = /export/desktops
read only = no

[Shortcuts]
path = /export/shortcuts/
read only = no