Ok, the nmap command output says if all samba sub-processes are running correctly. Here’s the expected output:
$ nmap nsdc
Starting Nmap 7.60 ( https://nmap.org ) at 2018-06-07 09:19 CEST
Nmap scan report for nsdc (XXXXXXXXXXXXXX)
Host is up (0.00015s latency).
rDNS record for XXXXXXXXXXXXXX
Not shown: 987 closed ports
PORT STATE SERVICE
53/tcp open domain
88/tcp open kerberos-sec
135/tcp open msrpc
139/tcp open netbios-ssn
389/tcp open ldap
445/tcp open microsoft-ds
464/tcp open kpasswd5
636/tcp open ldapssl
3268/tcp open globalcatLDAP
3269/tcp open globalcatLDAPssl
49152/tcp open unknown
49153/tcp open unknown
49154/tcp open unknown
Under some conditions related to upstream updates the kerberos-sec and kpasswd5 are missing and authentication stops working. Please check your.
Can you see the accounts list under “Users and groups” page?
This command should fail and show the error you see in the UI
/usr/libexec/nethserver/list-users administrator
Could you check also your DNS/SSSD/Kerberos config
config show dns
config show sssd
config show nsdc
systemctl status dnsmasq
systemctl status sssd
cat /etc/krb5.conf