[Samba] Windows Server 2003 and Samba 4.7.6

[Konstantin Boyandin]

Hello,

In short: there's a Windows Server 2003 system, which worked without 
many problems with NT domain (Samba 3). The NT domain is being shut 
down, and I noticed I have hard time trying to befriend the mentioned 
system with AD run under Samba 4.7.6 (default on Ubuntu 18.04).

Is the mentioned AD incompatible with Windows Server 2003? When trying 
to join, I get cryptic message about password being incorrect (? the 
domain administrator I use is used with correct password), and see no 
mentioned system name/IP in Samba logs.

(yes, I know that the Windows Server 2003 is a relic and should better 
be left in /dev/null, but it's still required and is run in isolated 
environment)

I would appreciate any piece of advice (or confirmation that this OS is 
not actually supported anymore). Thanks in advance.

Sincerely,
Konstantin