Windows clients not able to join to a domain hosted by qnap nas

[tamaspalm]

Hi All,

I am pretty new in networking and I bumped into a challenge that I am not able to solve for three days. What I would like to achieve is to join a windows server (windows server 2016) and Windows 10 clients to an active directory domain hosted by TVS-473e.

I tried to follow the available tutorials and read all the available documentation by qnap. here for exaample pretty well describe what I want: https://docs.qnap.com/nas/4.2/SMB/en/in ... roller.htm

What I managed to do :
- I enabled the domain controller - have the domain name set-ut with "domain_name".local format
- I have domain users and groups and able to authenticate and see the shared folders with their respected user rights (from qnap applications)
- In the dns setting I see my domain three with the "domain_name".local as well as the _msdcs."domain_name".local

- On the windows server 2016 - I have set up a fix IP and for the DNS server I have set up the preffered as 127.0.1.1 and as alternate 8.8.8.8 (this is the same which is set up for the nas in the network / virtual switch set-up.

however when I try to add the windows clients to a domain (same way as it is described here in the last point: https://wiki.samba.org/index.php/Joinin ... o_a_Domain) or either in power shell, I got the following error:

The following error occurred when DNS was queried for the service location (SRV) resource record used to locate an Active Directory Domain Controller (AD DC) for domain ""domain_name".local":

I see that there is something with the dns as in the nslookup my domain name is cannot be resolved in the local network however I have no idea how I could overcome this. I really appricate some guides here.Thanks in advance

Tamas