A family of Microsoft relational database management systems designed for ease of use.
Again, your support team apparently has direct access to the customer's network so they can verify the accdb is where it's supposed to be?
Also, there's the issue of the connection dropping apparently. "...the RDP connection simply drops. "
That implies some problem with the way that company's infrastructure is configured or supported. Nothing that we can help you diagnose.
In short, it's probably a coincidence to some extent that the missing file is an Access file, i.e. an accdb. And, while we are certainly interested in finding a resolution, there's little Access developers can do in that regard. Perhaps a search for support sites for RDP configuration and deployment will get you closer to the necessary expertise.