Exchange 2007 to 2013 Migration Outlook Anywhere keeps asking password

Question

Hi all, 
i'm migrating an Exchange 2007 Server with all roles installed on a Windows Server 2008 R2 to 2 Exchange 2013 SP1 Servers (1 Cas and 1 Mailbox) installed on Windows Server 2012 R2.
I installed Exchange 2007 SP3 RU13 for coexistance and everything was ok until i switched to the new 2013 CAS. 
After that the client using Outlook Anywhere started asking for password. 
I configured the Outlook Anywhere with these settings:
Exchange 2007:
OA Hostname mail.domain.com
Client Authentication NTLM
IISAuthenticathion Basic, NTLM
SSL Required True
Exchange 2013
OA Hostname mail.domain.com
Client Authentication NTLM (Both internal and external)
IISAuthentication Basic, NTLM
SSL Required True (both internal and external)
Before switching to 2013 Cas everything works smoothly and the Outlook clients receive NTLM as HTTP Proxy authentication.
After switching to 2013 Cas, test users migrated on 2013 Mailbox Server are ok, but Outlook users on Exchange 2007 Server get Basic as HTTP Proxy authentication and continue asking for credentials. 
In the Exchange 2007 server i configured the host file to resolve servername and servername.domain.local with the ipv4 address to avoid issues regarding IPv6 with OA in Exchange 2007. 
Using Microsoft Connectivity Test i receive the error "RPC Proxy can't be pinged - The remote server returned an error:
(500) Internal Server Error"
Any Ideas?
Thanks for your Help

Answer 1

Run this and post the result
https://testconnectivity.microsoft.com/
Cheers,
Gulab Prasad
Technology Consultant
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