IOS devices cannot register device to the wireless network

[joram_laureys]

We have a zonedirector 1200 (9.12.3.0 build 28) and ruckus zoneflex 600 AP's. We want the teacher in our school to register their device with zero-it. This works well for all android and windows devices, but for most IOS devices this does not work. When they get to the 'zero-it portal site' and click register device, nothing happens. When we try to 'bypass' the portal site by going to wifi.ourdomain.com/activate, they can enter the username and password. But again nothing happens. Any ideas ? 

[joram_laureys]

We've done the reset on the zonedirector to the default ruckus certificate. It was a ca certificate we made for free from startssl. It worked great on windows/android en older versions of IOS. Only on the newest version of ios we had alot of problems.