They are not one captive portal.
When connecting to a hotel hotspot, it is the hotel’s router that runs the captive portal service, and client devices (including the travel router) authenticate to the hotel’s router.
The captive portal that we have stopped maintaining is the captive portal service running on the travel router, which is used for authentication other than Wi-Fi passwords from client devices (your mobile computer) to the travel router.
The solution for connecting to hotel hotspots in older versions is still available: