Self-Signed Certificates and TTS (Google Cast)

I recently configured a self-signed certificate to be used internally (HA not open to the internet) in order to setup an integration that requires SSL. The thing is now my TTS integration is broken as outlined here.

I am having a hard time figure out how to get this to work again. Right now I am receiving the following error when an automation requires casting to my Google Home:

Failed to cast media ... Please make sure the URL is: Reachable from the cast device and either a publicly resolvable hostname or an IP address.

Any idea how to get around this?

Not sure if this will help. I have used this guide to create local ssl certificates.