Custom Location Limit By IP Address

[sonoracomm]

I'm new to NPM and Nginx, so I apologize if I'm making an obvious error.

I have a working configuration of Vaultwarden (Bitwarden) with NPM as the reverse proxy, even websocket.

I would additionally like to limit access to the /admin URL to internal IP addresses.

Unfortunately, no matter what I enter for the custom configuration, the proxy host shows as offline (red dot under Status).

Can anyone point me in the right direction to find a solution?

Thanks,
G