NAV 2016 Helpserver

Hello,

I have installed NAV 2016 and it's Helpserver on Windows 2008 R2, but the sites are showing incorrectly. After i press F1 the page is loading the menu but not the content or on some clients the content is not showing completely. Helpserver 2013R2 and 2015 was working fine on die same machine. I also tested the Helpserver on a Windows 2012 R2 Server with same result. I am doing something wrong or is this an known issues?

Thanks
Dany