How to forward Home Assistant to a subdomain with it being unable to connect?

I’m running Home Assistant on a Windows Machine, and can access it internally from
192.168.2.203:8123

I also host several other websites from my house (Garage actually). Some I tie to subdomains for easy remote access. Like my build server for games\apps I work on.

When Home Assistant is tied to Home.MyDomain.com, I get a login page I can access anywhere, but after logging in I get the following error:

“Unable to connect to Home Assistant”
RETRY

I’ve got the reverse proxy setup via my Linux VM, and the subdomain setup in the Godaddy DNS dash.
Running 0.86.6 on a Windows 10 VM.