Login to Identity Server using another Identity Server - OAuth2

Start 2 Identity Servers. Start the 2nd Identity Server with a port offset of 1 as described here.
Configure an OAuth/OIDC service provider in the 2nd Identity Server as described in here.

Callback Url: https://localhost:9443/commonauth
Create an identity provider in the first Identity Server as described in here.
- Enable OAuth2/OpenIDConnect: selected
- Default: selected
- Client Id: (client id of the service provider registered in second identity server)
- Client Secret: (client secret of the service provider registered in second identity server)
- Authorization Endpoint URL: https://localhost:9444/oauth2/authorize
- Token Endpoint URL: https://localhost:9444/oauth2/token
- Callback Url: https://localhost:9443/commonauth
Edit the service provider in the first Identity Server and select the Federation Authentication for Authentication type in Local and Outbount Authentication Configuration. Then select the created identity provider from the dropdown menu in Federation Authentication.
Now you can setup playground sample and try the authorization code grant as described here. You will be redirected to 2nd Identity Server instead of the 1st Identity Server for authentication.