Remote Home-Assistant

How to configure the host instance to relay the integrations from remote? I have done the configuration, but no integrations are showing up in the hosts list? I did a HACS install.

Are you talking about this integration? https://github.com/custom-components/remote_homeassistant

What is your configuration?

Correct.
I did a HACS install and the configuration within the UI, so nothing in configuration.yaml, except for the required two lines in the remote instance.

What I can’t do is any configuration on the remote host, when clicking configure there is an error message “500 Internal Server Error Server got itself in trouble”. I thought that there was no need to configure anything on the remote instance, but I realize that this is probably the cause?

Did you open an issue on gitHub where the developer is sure to see it & help you?
This forum is primarily for support of core HA features, not community ones.