Exchange 2010 & 2016 co-existence owa access issue

I have added two Exchange2016 servers to existing exchange2010 farm. Exchange2010 has 2 cas & 2 mbx servers in a DAG. I have configured Virtual Directory internal/external url to be the same as existing url. Everything looks good except I can't log into from exchange2010 OWA to a mailbox located on exchange 2016 MBX. I got error :

A server configuration change is temporarily preventing access to your account. Please close all Web browser windows and try again in a few minutes. If the problem continues, contact your helpdesk.

If I logon directly using exch2016server.domain.com, it works. When I log on a exchange 2016 web interface to a mailbox located on exchange 2010, it also works. It seems that exchange2010 cas server isn't proxy to exchange 2016. I run command 

Get-ExchangeServer |Get-OwaVirtualDirectory|fl servername,*auth*

and exchange2010  InternalAuthenticationMethods : {Basic, Fba, Ntlm, WindowsIntegrated}

exchange2016 InternalAuthenticationMethods : {Basic, Fba}

is this the reason the proxy