Migration Exchange 2010 to Exchange 2013 - Unable to access Public Folder

Hi Exchange Experts,

Exchange 2010 to Exchange 2013 migration in co-existence phase. I migrated my mailbox to 2013 and now I am not able to access the public folder. I don't want user loosing access to public folder after I move them to 2013.

Error: when I try to access the public folder, it will ask for credential and once entered this is the error I get:

"Cannot expand the folder. Microsoft Exchange is not available. Either there are network problems or the exchange server is down for maintenance.”

I have enabled Outlook Anywhere on both the servers:

                            Exchange 2013 server:
                            ExternaHostname : mail.abc.com
                            InternalHostname : mail.abc.com
                            ExternalClientAuthenticationMethod; NTLM
                            InternalClientAuthenticationMethod ; NTLM
                            IISAuthenticationMethods           : {Basic, Ntlm, Negotiate}
                            ExternalClientsRequireSsl          : True
                            InternalClientsRequireSsl          : False

                            Exchange 2010 server:
                            ExternaHostname : mail.abc.com
                            InternalHostname : (blank)
                            ExternalClientAuthenticationMethod; Basic
                            InternalClientAuthenticationMethod ; Ntlm
                            IISAuthenticationMethods           : {Basic, Ntlm}
                            ExternalClientsRequireSsl          : True
                            InternalClientsRequireSsl          : False


                    Please help!

Thanks,