Both Turnkeys are in default configuration with changing domain name to NET.LAN (ver.15) and NET1.LAN (ver. 16) with
other DNS (192.168.9.100 - ver. 15, 192.168.9.57 -ver.16)
Joining to the ver. 15 is success

(Asking about creditentials of Administrator)
Trying join to the ver. 16 returned the message:
"Can't contact with domain controller oo Active Directory (AC DC) for "net1.lan "
Looks like WIN10 can't find DC in ver.16 -because of Kerberos ? any protocol ?
The same machine join to the turnkey domain controller in ver. 15.00 without any issue.

Any ideas?