@mr_jinx
The "value", according https://developer.apple.com/news/?id=q78sq5rv must be a JSON API file.
This file shows an example how the connection phase works.
As you can see, this file doesn't contain a static value.
An non logged in device would retrieve :
{
"captive": true,
"user-portal-url": "https://example.org/portal.html"
}
After login, the same JSON API file could show :
{
"captive": false,
"user-portal-url": "https://example.org/portal.html",
"venue-info-url": "https://flight.example.com/entertainment",
"seconds-remaining": 326,
"can-extend-session": true
}
The good new : IPv4 and IPv6 ready.
This will simplify the "get the login page shown to the client" a lot.
'https' isn't an option here : your portal will need valid certificates.
From what I understood, IPv6 is still optional.
I played with this 'DHCP 14' option, and it worked well.
Dono / didn't test any Android devices ....
edit : this is still 'draft' .....