CMN or CMG fails with 'The supplied credentials failed. You must correct them before advancing.' (4321434)

• When configuring 'Directory Connector | Source/Target Server Information', Coexistence Manager for Notes (CMN) or Coexistence Manager for GroupWise (CMG) fails with "The supplied credentials failed. You must correct them before advancing."
• Monitoring the LDAP connection with ADInsight shows that "STRONG AUTH REQUIRED"

Resolution 1

Enable simple binds:

• Go to Default Domain Controllers Policy | Computer Configuration | Windows Settings | Security Settings | Local Policies | Security Options
• Set 'Domain controller: LDAP server signing requirements = None'
• Set 'Network security: LDAP client signing requirements = Negotiate'

Resolution 2

Enable SMB signing & SSL and configure CMN or CMG to connect over SSL.