makeWebRequest not working on device with Let's Encrypt certificate

Hi,
I've been struggling the last day with getting my app to work on my device.

With a let's encrypt certificate it's working fine in the simulator, but on my Fenix 7 pro it's failing with error code 0.

I've tried different server configurations (both nginx and apache), but with no luck.

The nginx server config is setup with fullchain, and is getting "A" ranking on test tools. But maybe I'm still missing something.

It seems to me to be quite a widespread problem on garmin devices, and seems like something garmin should sort out (I would guess they are not trusting some part of the Let's encrypt chain), but I'm hoping that there is something I can do to sort it out myself, that does not include buying a $50/year premium cert for a toy app.