Alexa Echo devices accessing Home Assistant entities/scripts (Home Assistant behind reverse proxy)

I currently run Home Assistant VMware VM on a Windows 11 Host with Bridged Networking behind an NGINX reverse proxy: https://hassio.mydomain.com

Sometimes when I start/restart Home Assistant VM, Alexa devices say the message “Device isn’t responding. Please check its network connection and power supply”, However, Home Assistant has no issues controlling any of its devices.

How do Alexa devices reach/talk to Home Assistant? Is it via TCPIP V4 or TCPIP V6? Would Alexa devices try to reach Home Assistant via https://hassio.mydomain.com/* ? If so, I’m guessing maybe something might be wrong with my NGINX configuration for Home Assistant?

Is there any way to see the related errors in the Amazon cloud when Alexa devices can’t reach Home Assistant endpoint?

Does anyone have any useful tips that could help me narrow down the issue?