Steps:

$ npm run dev     # or run preview
...

Use the port forwarding tool, check that it works.

Stop the server. Restart.

Expectation

Tool forwarding remains until it's terminated in its window.

Actual

Port forward stops when such a port is closed in the VM.

Suggestions

The script could try to reconnect (in a loop).

Also check that the daemon mode (-d) works the same.