Hi, and welcome.
Easier question first:
I see at the bottom of the browsers that a javascript will be excecute, so need i Java for correct working?
To my knowledge nothing in Zentyal requires Java. JavaScript, which is something different, probably needs to be enabled within the browser. That's generally the default setting for most popular browsers.
... like a loop.
I have seen that behavior (and others have reported it) but I don't know the cause for certain. Based on my experience, that behavior is rare if the user actually logs out of the captive portal session rather than simply closes the browser. By default, a captive portal user's session remains alive for a brief period of inactivity (I can't rememer the default time period
). My suspicion is that the session needs to die to keep the loop behavior from happening.
I have successfully tested the captive portal under iOS Safari, Internet Explorer, and whatever browser is being used on a Kindle Fire.