I guess i'm not that clear about the network i'm running.
My network has about 10 public access points all ubiquity, spans about 10 hectare or 25 acres.
I physically devided the network in segments, all connect to the pfsense server to its own network card.
All networks have its own dhcp server with different ranges, 10.20.1.1/24, 10.20.2.1/24, etc.
but all connect to the same captive portal, opt1.
All this was done for containing problems to a smaller sector, if problems araise (which did, multiple times) it doesn't bring the whole network down.
So this is why when people wander from one side of the site to the other they have to login again each time.