Samba4/function/level - Ab wann greift der Eintrag?

Hello,

i’ve set up a fresh ucs master server and want to join it to my windows domain running with a 2016 server, where a forest and domain level of 2012R2 is active.
I found the UCS variables samba4/function/level which is 2008_R2 after installing the domain controller and changed it to 2012_R2
But the domain and the forest level of ucs dc remains at 2008_R2 level.
If i use the given options with samba-tools, i get always the error message “ERROR: Domain function level can’t be higher than the lowest function level of a DC!”

I just set up the ucs sytem, created the domain during setup and after the installation was finished i installed the domain controller app, because before i didn’t had the ucs variable samba4/function/level or the samba-tools available.

How is the correct way to raise the forest level?
As the windows domain is running with exchange 2016, i don’t want to lower the level on the windows dc at the moment. But i’m not sure if 2012_R2 level is needed for exchange…

Greeting,
Michael