[Samba] winbindd does not detect its client site

[Felix Matouschek]

Hello,
 
I have two DCs running Sernet Samba 4.2.3, each DC has its own subnet and own site. They are both at different locations.
 
When running "net ads lookup" both show the respectively other DC as active DC for authentication.
 
They recognize that the other DC is not the closest DC but use it anyways, the value for "Client Site Name" just stays empty.
 
The behaviour of the clients is somewhat irrational. Some do honor their site, some use the DC of the other site and have an empty "Client Site Name".
 
Is there anyway to teach "net ads" / "winbindd" to use the correct site?
 
Greetings,
Felix