Outlook Anywhere can't connect to Exchange via UAG server with error "the request was unable to reply to an HTTP 401" from application log RRS feed

  • Question

  • Hi Experts,

    We get very strange issue Outlook Anywhere can't connect to Exchange via UAG server. However OWA and mobile mail working. The Outlook anywhere is showing as connecting and we see the warning

    Name:      Application
    Source:        Microsoft Forefront UAG
    Date:          5/9/2017 4:13:06 PM
    Event ID:      24

    The request from user domain\user at source IP address to
    trunk mail; Secure=1 failed because the request was unable to reply to an HTTP
    401 request from application MAIL-OA of type ExchangePub2013. The session ID is

    this is our network topology:


    User-->Internet |                      |----->Exchange 2013


    The strange issue is the issue only happens when user connect outlook viaUAG1 server, if via UAG2, Outlook anywhere always working. Any suggestions will be highly appreciated.

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    Monday, May 15, 2017 9:39 AM