Outlook login prompt when outside the LAN

Hi @ashish maliks ,
What's the type of your account(Exchange on premises, Exchange online or Microsoft 365)?

I am facing Basich Auth prompt when I open Outlook when disconnected from the VPN.

Did the issue only happen to this specific account? And could other accounts in your client work normally?
Do other users in your organization also have this issue?

If other accounts could work normally on your Outlook client, the issue may be related to the account instead of Outlook. Based on my research, the Auto Discover Settings in server/Outlook may affect it, to further analyze and troubleshoot your issue, please first try to use "Microsoft Remote Connectivity Analyzer"(Outlook Connectivity and/or Outlook Autodiscover test ), based on the outcome you(or the Exchange Administrator) could check the errors in the report.

If you still have other questions about this issue or that's not your case, please provide me with more information(such as the version of Outlook, account type etc.) and I would continue to research it with you.

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