Windows 7 client cannot connect to Zentyal 7 fresh installed server

[ATT1]

Hello,
I just installed a fresh Zentyal 7 server. I can connect to samba and shared files via entering "\\10.9.0.1" with Windows 10 (yes that is a VPN IP adress).
When I try to do the same in Windows 7, the client also asks me for username and password, I enter MYDOMAINNAME\myusername and my password, everything is correct, but I always get the error "unknown username or wrong password".
The same Windows 7 client previously perfectly connected to the Zentyal Samba domain. I searched for old stored certs of the old server etc. but did not find anything on the client.
Do I need a sort of fallback to old protocol mechanism for Samba, so that Win7 works again, or is it entirely the clients' fault, and if yes, what has to be changed in the client (Win7 64 bit) ?

[zyzio]

paste the result

testparm -vs | grep "min protocol"

[ATT1]

Load smb config files from /etc/samba/smb.conf
Loaded services file OK.
Server role: ROLE_ACTIVE_DIRECTORY_DC

        client ipc min protocol = default
        client min protocol = SMB2_02
        server min protocol = SMB2_02

[zyzio]

testparm -vs | grep "ntlm"

[ATT1]

# testparm -vs | grep "ntlm"

Load smb config files from /etc/samba/smb.conf
Loaded services file OK.
Server role: ROLE_ACTIVE_DIRECTORY_DC

        ntlm auth = ntlmv2-only

[zyzio]

https://forum.openmediavault.org/index.php?thread/38336-smb-shares-inaccessible-on-windows-7-and-10/

[ATT1]

Okay  and how do I add the options
ntlm auth = ntlmv1-permitted         
and
ntlm auth = yes
to the Zentyal system so it is permanent and will not be messed up next reboot, etc.  ?

[zyzio]

Do you have all windows 7 updates installed?

[ATT1]

Perhaps not all Win7 updates, but at least SP1 and then some.

[zyzio]

I have machines with windows 7 and there are no problems with the domain -> update windows 7