Microsoft OLAP Windows Authentication Issue

My company change their existing domain (xxxx.com) to a new domain (XXXX.local) and realize that the Refreshable Excel using OLAP query is not working on VPN anymore (It is working before the AD migration)

These are the troubleshooting steps done from my end

1. Firewall logs showed the traffic to the database server is all successful
2. Query DNS port 53 and 389 LDAP to both Domain Controller is successful as well

Then I decided to test using runas “NEWDOMAIN\Users” and launch the refreshable excel, and it was able to refresh successfully

I wonder what am I missed out on in the troubleshooting step. Appreciate anyone who can advise me on how to troubleshoot further