@Mario_Lanno
I was also experiencing problems joining WIn 10 client to our NT4-style domain.
My domain name was JIMBO.COM .
I succesfully joined Win XP an Win 7 clients, no chance with Win 10.
After applying the registry patch without unnecessary values, I renamed my domain from JIMBO.COM to JIMBO-DC (according to Nethserver Admin Guide).
Once modified the domain name, I’ve been able to enlist my Win 10 client into JIMBO-DC.
This is the patch applied:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanManWorkstation\Parameters]
"DNSNameResolutionRequired"=dword:00000000
"DomainCompatibilityMode"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\Protect\Providers\df9d8cd0-1501-11d1-8c7a-00c04fc297eb]
"ProtectionPolicy"=dword:00000001
No other values required.
Hope this helps.
Cheers.
PS: to remove unwanted values from registry key, just put a hyphen after equal sign in your *.reg (i.e. "ProtectionPolicy"=-)