LDAP issue after hardening both Domain Controllers

Hi team,

Recently I had been asked to apply some GPOs to both Domain Controllers in order to improve security. I applied them and after restarting both Domain Controllers the LDAP protocol stopped working as we expected. 

LDAP works if a Microsoft servers sends the query, but if we  try to use LDAP from Linux it doesn't works.

Running Wireshark on one of the DC I've got the following messages:



LdapErr is the following:

LDAPMessage searchResDone(182) operationsError (000004DC: LdapErr: DSID-0C0907C2, comment: In order to perform this operation a successful bind must be completed on the connection., data 0, v2580) [0 results]
    messageID: 182
    protocolOp: searchResDone (5)
    [Response To: 7]
    [Time: 0.000252000 seconds]

Already rollback the following GPOs for DC, and this is how they are now:

Network security: LDAP client signing requirements - None
Domain controller: LDAP server signing requirements- None
Domain member: Digitally encrypt secure channel data (when possible) - Enabled 
Domain member: Digitally sign secure channel data (when possible) - Enabled 

What else can be causing this LDAP behaviour?

Thanks in advance,

Will