Could not connect to accounts provider

NethServer Version: NethServer release 7.6.1810 (final)
Module: Account Provider

I fill the form for Account Provider, every seems fine, but if I go to “Domain accounts” on the Web GUI it says:

“Could not connect to accounts provider!”

However I can query about a domain user from a cli:

id ldap
uid=1042601118(ldap@example.com) gid=1042600513(domain users@example.com) groups=1042600513(domain users@example.com)

More configs:

account-provider-test dump 
{
   "BindDN" : "NAOS\\TINY-FISHWIFE$",
   "LdapURI" : "ldap://dc000.example.com",
   "DiscoverDcType" : "dns",
   "StartTls" : "1",
   "port" : 389,
   "host" : "dc000.example.com",
   "isAD" : "1",
   "isLdap" : "",
   "UserDN" : "DC=example,DC=com",
   "GroupDN" : "DC=example,DC=com",
   "BindPassword" : "supersecret",
   "BaseDN" : "DC=example,DC=com",
   "LdapUriDn" : "ldap:///dc%3Dexample%2Cdc%3Dcom"
}

config show sssd 
sssd=service
    AdDns=192.168.34.4
    BaseDN=DC=example,DC=com
    BindDN=
    BindPassword=
    DiscoverDcType=dns
    GroupDN=DC=example,DC=com
    LdapURI=ldap://dc000.example.com
    Provider=ad
    Realm=EXAMPLE.COM
    StartTls=enabled
    UserDN=DC=example,DC=com
    Workgroup=EXAMPLE
    status=enabled


config show dns
dns=configuration
    NameServers=192.168.34.4

Please could you help me to solve the problem?
TIA

How many DCs are there? Can you ping them all?

Can you find any relevant error message in /var/log/messages?

Could you attach the output of

net ads info

Well, It seems that the problem was in smb.conf of de SAMBA AD DC:
I have an incorrect ip in dns forwaders, I’ve changed, restart the samba service and voilá!
HTH