Mobile device ID changed randomly for Exchange 2016

EKSG 45 Reputation points
2023-03-27T08:08:13.6433333+00:00

During the past month, I have encountered users' devices being quarantined by our Exchange 2016 despite it being approved previously for Exchange access. Upon investigation, I observed that the physical device is still the same (tallying the serial number of the physical device against my records), but the device ID in Exchange is different (attached picture as shown).
All affected users are using Microsoft Outlook on various Android smartphones. As of now, it is time consuming as I have to verify each user's phone physically to make sure that is the same device that I had previously approved.

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Exchange Server
A family of Microsoft client/server messaging and collaboration software.
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  1. Andy David - MVP 139.4K Reputation points MVP
    2023-03-27T11:36:13.13+00:00

  2. m49808 5 Reputation points
    2023-03-31T13:20:57.7466667+00:00

    I have confirmed via a support case that this is expected and nobody should rely on device id for access rules. It can and will change and they cannot say how, why, or when. Could be tomorrow, could be years from now. No way to know.

    Instead just allow the Outlook device string (at the cost of security!), move to exchange online, or use Hybrid Modern Authentication.

    Unbelievable.

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