How to understand what and where blocks UZ in the domain?

Question

Active Directory

Good morning! Periodically, something blocks the UZ in the domain, because of this, backup on the servers fails. How to understand what and where blocks UZ in the domain? The audit shows only such an event, but nothing is clear from it:

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
  <Provider Name="Microsoft-Windows-Security-Auditing" Guid="{54849625-5478-4994-A5BA-3E3B0328C30D}" /> 
  <EventID>4740</EventID> 
  <Version>0</Version> 
  <Level>0</Level> 
  <Task>13824</Task> 
  <Opcode>0</Opcode> 
  <Keywords>0x8020000000000000</Keywords> 
  <TimeCreated SystemTime="2018-10-07T02:09:45.330890800Z" /> 
  <EventRecordID>5750135</EventRecordID> 
  <Correlation /> 
  <Execution ProcessID="584" ThreadID="624" /> 
  <Channel>Security</Channel> 
  <Computer>wsdc-01.domen.local</Computer> 
  <Security /> 
  </System>
- <EventData>
  <Data Name="TargetUserName">backup</Data> 
  <Data Name="TargetDomainName" /> 
  <Data Name="TargetSid">S-1-5-21-3362886647-1212668267-832902950-11833</Data> 
  <Data Name="SubjectUserSid">S-1-5-18</Data> 
  <Data Name="SubjectUserName">WSDC-01$</Data> 
  <Data Name="SubjectDomainName">domen.local</Data> 
  <Data Name="SubjectLogonId">0x3e7</Data> 
  </EventData>
  </Event>