External Server Pull Files From Internal Server

I have an application that needs to pull files from an internal server. This
is the setup. The web server is external facing, meaning exposed to the
internet. I then have a file server that sits inside our domain. I created a
COM object that can impersonate a user to retrieve files from that server.
However, I cannot get the application to pull files from the internal server.

I first tried a domain account that could reach both servers. This did not
work. I then had the network team create the same account on both machines.
This is not working either. I can impersonate the user (I am able to get the
user/users authenticated), but the script keeps coming back with and access
denied. Code: