MFA for External network

I’m looking to allow external access to my Home Assistant systems, from a different domain externally to the internally network (reverse proxy). I know i need to trust the domain (not an issue).
I would like to tighten the security for the external domain by using MFA. but not for the internal network. Although I still want to authenticate on the internal network. so trusted networks will not work as there is no authentication.
Is there a way only to enable MFA from the external network / domain ONLY.

Kind Regards

I know this is old, but did you get this working as you wanted?