Hi Sorry to inform you that Exchange Server 2016 Installation ( In current form CU2) is not supported on Windows Server 2016 and since Server 2016 final version is not officially announced by Microsoft, it will take a while that the updated information get published. My advice is to install it on windows server 2012 r2 for now. Good Luck
Interesting. I just last week migrated my personal domain to Exchange 2016 CU2 on Server 2016. It is all working just fine currently. However, before I actually migrated from Exchange 2013, I noticed that the Exchange cmdlets weren't available in Powershell. I delayed my migration until after the latest Windows CU which fixed it. Is your server up to date? (you've installed KB3189866 and your build is 14393.187) and it's having problems? You checked in IIS and the website(s) are running? Sometimes it will put an extra binding in there that will keep one of them from starting.
Now it is Supported Info: blogs.technet.microsoft.com/exchange/2016/09/20/released-september-2016-quarterly-exchange-updates Download: microsoft.com/en-us/download/details.aspx?id=53837