Fails on localhost homeserver

[JWCS]

Describe the bug

Access to private network server gotten by proxied port.
Host server: http://localhost:6167 (or) http://127.0.0.1:6167
(Definitely doesn't work without http:// prefix).
Type in username/pass (tried both username as @ME:server.name or as just ME)
Error msg:
Failed to find your Matrix ID server.

Reproduction

1. Start sable
2. Hostserver: http://localhost:6167
3. User/pass

Expected behavior

Login

Platform and versions

1. OS: Windows 11
2. Sable win client: v1.17.0
3. Privately hosted matrix server

Additional context

Works for element win client, so I know it's partially working. Works for other devices when I can dns provide them url.
If this is based off of cinny, that was also broken, and I filed a mirror bug report there:
cinnyapp/cinny#2974