Recent trend with iPhones on unleashed

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I keep hearing from clients that users with apple devices cannot connect to an unleashed network wifi.  The WLAN is using a hotspot service with a landing page redirect.  It is common that users with any device will need to browse to any page to trigger the landing page (rather than it popping up automatically), and also have to click through the certificate/privacy warning.  The situation I keep hearing is that apple devices cannot connect at all.  If they connect, they are totally unable to get to this landing page.  I have found that all of the issues thus far have come from locations running 200.3.9.13.228.

Has anyone else experienced this trend and found a fix?  Might this due to a recent update to iOS?  I am not sure if this might be stemming from the devices themselves or the users of these devices..