DirSync: Agent Error connecting to endpoint: The LDAP server is unavailable. (Discovery failing) (4289090)

POSSIBLE CAUSE 1
This error occurs when IPV6 is disabled on the Agent Server.

POSSIBLE CAUSE 2
Something is wrong with the domain controller (DC).

POSSIBLE CAUSE 3
The is an Issue with the service account.

POSSIBLE CAUSE 4
The Domain Controller IP address changed and the IP Address stored in our SQL DB is incorrect.

For POSSIBLE CAUSE 1
Enable IPV6 on the Agent Server, and restart the Directory Sync Agent Service on the agent server and rerun Discovery

For POSSIBLE CAUSE 2
Add a second domain controller with the PDC role. 

The first workflow run can take longer than usual to complete. An extended runtime is to be expected if the jobs have been failing for a while as they will need to catch up.

For POSSIBLE CAUSE 3
Ensure that the service account is a direct member of domain admins and not a member of a group which has been added to domain admins.

For POSSIBLE CAUSE 4

• Uninstall the Dirsync agent in the specific environment causing this issue.
• From Dirsync Environment create a New Agent.
• Install the agent on the agent server, and use the new registration ID.
• If this does not resolve the issue:
  • Contact Support and request to have a remediation run to update the IP address in the Domain Controllers SQLDB.
    • Provide the Environment name
    • Server Fully Qualified Domain Name (FQDN)
    • Server IP Address