GWT RPC call not firing

Hi,
I am new to GWT but have to deal with a prod issue in a GWT application.

There is a page in the application that displays a GWT grid. Upon page load, there are also RPC calls to retrieve data for the grid and user entitlement. The application runs on a Tomcat server in US.

When users in US hit this page, it opens up with the proper data.
However, when users in HK hit the same page on the same Tomcat instance from a HK desktop, they get a blank page with a yellow icon indicating javascript error on the browser status bar.
They have to hit the F5 button and then the page would render with the proper content.

We compared the access log of Tomcat between the first failed hit and the 2nd successful one. The only difference is that the successful log contains lines for POST request for those RPC calls.
At this point, we are not sure if this is a coding issue or some sort of machine setting issue or a network latency-related issue.
Has anyone experienced such issue? How should we continue with the investigation?

Thanks for the help.

T