When you say "I cant connect a windows desktop on the same subnet to the Domain". Do you mean you can't join the domain? Or that you can't connect to the server at all? Or something else altogether?

If it's the former, then I have no idea OTTOMH. But if you can provide more info, such as Samba and/or Windows error logs, plus further info about any error messages that you may be seeing then perhaps I can assist further?

Having said that, the first thing that comes to mind there is time sync. Windows requires that the server and the client are both the same time. I discussed that earlier in the year within another thread which might be worth looking at if the issue is joining the domain. Within that thread, I also provided a link to the Samba wiki page for joining a Samba domain - which may be of use?!

If it's that you cannot connect to the server at all, then it sounds like it could be a networking issue?! When you say that "Network is configured with NAT on an internal network", I assume that you mean that the connection to the internet is NATed (rather than the server directly itself) and that there is no internal restrictions or firewalling that might stop the client from connecting to the server?

If networking is potentially the issue, can you ping the server ok from the Windows machine? Can you view the server's landing page via a browser on the Windows machine? Have you double checked that you don't have an IP clash (i.e. 2 machines using the same IP address)?

I'm no Samba expert and don't use Windows at all these days, but I know the internals of TurnKey quite well. If you can assist me to understand exactly what you are doing when the issue occurs and what is actually going wrong, then I may be able to assist. At the least I can likely give you some pointers.