From previous projects I know that Apple's Captive Network Assistant (aka WISPr client, too) runs a restricted browser, see How can I debug the browser in Captive Portal? and Ajax on Captive Network Assistant on iOS and OSX.
My hotspot is running a angularJS web page. On a Windows Phone 8.1 and an OS X Lion my angular page works fine. On my iOS 8.3 there must be a JavaScript error somewhere in the code, because I can see the angular variable expressions {{myVar}}
in the code which means the angular framework isn't loaded properly.
Any idea what could be the cause?