HTTP healthckeck not using hostname for SNI

Hello there. I’m running Traefik 3.6.13 and have troubles to get the healthcheck working for a HTTPS backend running on Apache. The healthcheck always fails.

My service configuration in Traefik looks like:

http:

...

  services:
    website-a:
      loadBalancer:
        servers:
          - url: "https://hostname-of-apache-server.example.org"
        passHostHeader: true
        sticky:
          cookie: {}
        healthCheck:
          hostname: "website-a.example.org"

Traefik gives me the following logs:

WRN Health check failed. error="checking HTTP health: received error status code: 421" serviceName=website-a@file targetURL=https://hostname-of-apache-server.example.org

On the Apache server I get the following error message:

[ssl:error] [pid ****:tid ****] [remote ****:****] ****: Hostname hostname-of-apache-server.example.org provided via SNI and hostname website-a.example.org provided via HTTP have no compatible SSL setup

It looks like Traefik is not using the configured hostname for the healthcheck for SNI. So Apache gets confused with that. I was expecting, that Traefik will use the specified hostname for the healthcheck also for SNI.

If you think this is a bug, then report it to the devs at Traefik Github.