hubPersons API got 401 error in specific time

Hi All,

I use hubPersons API in my scheduled integration at about everyday 17:40 (UTC+0) to get person's party_id.

Sample: https://xxxx.fa.ocs.oraclecloud.com/crmRestApi/resources/11.13.18.05/hubPersons?q=SourceSystem%3DFUSION_HCM%3BSourceSystemReferenceValue%3D300000005798636

It has returned 401 everyday since Jul 10, while I can get correct response in postman with same authentication.
Other Fusion REST APIs in same integration with same connection works fine.
and I run the integration manually at 4:00（UTC+0）, it will not show 401.

May I know why?