How to use relative urls for login/consent/logout pages?

[hesmar]

I would like to use hydra on an embedded device which has no fixed IP/Hostname. Therefore, it is necessary to redirect the user to the login and consent page using a relative url. Everything is behind a reverse proxy which defines the paths, so that the urls for the web browser become the following:

https://<dynamic_ip>/oauth      -> hydra services
https://<dynamic_ip>/ui/login   -> login page
https://<dynamic_ip>/ui/consent -> consent page
https://<dynamic_ip>/ui/logout  -> logout page

Looking at the configuration reference (https://www.ory.sh/docs/hydra/reference/configuration) it should be possible to set relativ paths:

## urls ##
#
urls:
  
  ## login ##
  #
  # Sets the OAuth2 Login Endpoint URL of the OAuth2 User Login & Consent flow. Defaults to an internal fallback URL showing an error.
  #
  # Examples:
  # - https://my-login.app/login
  # - /ui/login
  # 
  # Set this value using environment variables on
  # - Linux/macOS:
  #    $ export URLS_LOGIN=<value>
  # - Windows Command Line (CMD):
  #    > set URLS_LOGIN=<value>
  #
  login: https://my-login.app/login

But if I set the urls.login to the /ui/login, hydra tells me that this is not a valid URI:

hydra-hydra-1          | The configuration contains values or keys which are invalid:
hydra-hydra-1          | urls.login: /ui/login
hydra-hydra-1          |             ^-- "/ui/login" is not valid "uri"

Is it somehow possible to achieve redirection not knowing the full?