This is actually the splash page that users would see under certain circumstances such as Hotspot splash page or requesting network access when the access is disabled via a schedule. Given that these pages are dynamic, you’re seeing what you’re supposed to see.
If you switch that to HTTP, you should get a spinner like you see on the S8-PoE because this occurs when the device is managed and is by design. If the device was not managed yet, there would be a field for you to enter the hostname of your local controller (Appliance, Docker container, or LXD container).