System Configuration:

Dell Latitude E7240, Windows 8.1 pro, Outlook 2013 and Exchange Server 2013.

Problem:

It is fine when the notebook connected to office network. 

However, when I connected the notebook via 4G wireless, Outlook prompted for password.

What have I done so far?

1. Created a new profile
2. Added an entry in Registry for lmcompatibilitylevel and set to 2
3. Deleted credential of Outlook / Exchange from Credential Manager  
4. The password remain unchanged 

Please help me.

Thanks.

lc60504,

Assume that domain users connect to Microsoft Exchange Server by using Microsoft Outlook. The Outlook Anywhere feature is enabled in their Outlook profiles. When the domain users switch from using the LAN to using a wide area network (WAN), they are prompted for credentials by Outlook.

This issue occurs when the client authentication method of Outlook Anywhere is set to Basic Authentication on the Exchange server. When the user switches to another network, Outlook may change the connection type from TCP to HTTPS. If the client authentication method of Outlook Anywhere is set to Basic Authentication, the user is prompted for credentials.

To resolve this issue, set the client authentication method of Outlook Anywhere to NTLM Authentication on the Exchange server.

If your network connection is slow or unstable, Outlook may lose connection to the mail server. When Outlook try to reconnect, it will prompt for the credentials. Wireless is more likely a n unstable network.