I Migrated Exchange 2010 to Exchange 2013 server with 2 owa/cas on it. (network loadbalancer)

The user outside of the domein Keep getting a prompt asking for a login when starting outlook 2013/365.

Inside the domein its worksfine (Remote Desktop Services)

Other domeins work fine aswell

Hi,

Please check the Outlook Anywhere configuration in your Exchange server:

Get-OutlookAnywhere | fl Identity,*auth*,*host*

Additionally, we can run the following tool to check your Autodiscover service:

https://testconnectivity.microsoft.com/

Regards,