pycharm – How can I get JetBrains Gateway to pick a port other than 8000?

I am developing an application in PyCharm using the Remote Development feature. This creates as SSH connection to the host via JetBrains Gateway, then allows editing and running the remote code from a local IDE. I can successfully connect to the remote host and launch the IDE.

The application is configured to bind port 8000. However, when I attempt to launch it (from the command line or through the IDE) it fails to start with this error:

"connection to ('0.0.0.0', 8000) failed: [Errno 98] Address already in use"

If I disconnect the IDE, it starts correctly. If I connect the IDE and bind the application to port 8001 instead, it starts correctly. But for a number of reasons re-configuring the application is not an option. How can I reconfigure the IDE (or JetBrains Gateway) to use a port other than 8000?