I tried to install from scratch on an VM to try to reproduce the bug.
It wasn’t easy, since lot of issues happened, the install is not yet as straightforward as it should be. Especially, the system should update itself automatically during or just after the first install.
Regarding SOGO Ldap authentication :
After having installed the updates (not from the testing repo), then the Samba AD module, then configured it, then installed SOGO, there was something really unexpected : the system detected another LDAP server on the same subnet and decided to use it.
This other LDAP server is the one running on another nethserver running on the same subnet. Why did the installer choose that one and not the locally hosted one ?
So… I think I found another bug by chance @mark_nl 
More generally I believe that while it was certainly decided for really good reason, making the AD samba server reside in a linux container with a user defined IP address will more that certainly lead to mistakes and configuration headaches.
Don’t hesitate to ask if I can help further.
Matthieu