I have an MX unit setup to require everyone to login every 12 hours i.e. splash page pop up. What I have noticed is that it seems a little bit broken.
Google.com, Facebook, Apple, AirNZ pages all contiune to work without the splash plage coming up.
Crashplan, local news site, banking website all require me to login.
The Apple and AirNZ pages are not cached in my browsers history as I hardly every visit them, I have even tried another browser....
In short it doesn't seem like the enforcement of the requirement to login is working that well...
Under Access Control, what is your Captive Portal strength set to? Also, are any of those websites you mentioned in the walled garden by chance?
As Drew mentioned above, I'd assume that these domain names/IP's are resolving to addresses within the Walled Garden Ranges (Wireless>Access Control>SSID).
Hey sorry for the late reply, walled garden is disabled however Captive portal strength wasn't set to block all so I will see if that makes a difference, maybe it was allowing HTTPS traffic but blocking HTTP I didn't actually check that.
I'll post an update when I know more.