I am running Authentik in Docker accessible through https://auth.domain.tld. I setup Authentik in Nginx Proxy Manager as following:

r/Authentik - NPM Configuratiions — NPM Configuratiions

I have a couple of services I am trying to setup with Authentik Proxy Authentication. The services running on the same docker network as Authentik, I managed to configure with authentik docker host name and port in NPM configurations:

r/Authentik - Application NPM Custom Configurations — Application NPM Custom Configurations

This works and I am able to Authenticate into the applications successfully.
However, I also have external services that are not connected to Docker Network of Authentik. When using the Authentik Domain instead of its internal hostname i get

proxy_pass https://auth.domain.tld/outpost.goauthentik.io;

r/Authentik - Authentik behind NginX Proxy Manager: Embeded Outpost 500 Internal Server Error

In Authentik Container I am getting error=websocket: bad handshake

Can anzone help me find the correct NPM configurations for Authentik to be accessble? I found this guid but implimenting it into NPM did not help.