Fastify excel streaming

Hi,
I needed to generate and send large excel files from the server. functions do not support streaming, so added an endpoint for excel generation and downloading,
it is a post handler like api/download-as/excel, everything works fine on local, but when deployed on server, all I get back is the html file, index file I mean.
The way I trigger it from the browser is, https://my.site.com/.redwood/functions/api/download-as-excel
so I also tried this;
https://my.site.com/api/download-as-excel this did not work neither, this might be due to ingress rules I am not sure.
My app is running on k8s, behind kong gateway,
what is the proper way to handle/configure fastify routes and to making calls to them.

I doubled checked it and this turned out to be an ingress issue, after adding the path to the ingres rules, it started working fine.