[Samba] "failed to lookup DC info for domain over rpc" when joining samba4 domain

[Richard Connon]

Hi,

I have an existing samba4 domain with 2 domain controllers on different
sites.

Both domain controllers are running samba 4.1.17

Until recently the domain operated exactly as expected. I recently tried
to join a new machine to the domain and received the error:

Failed to join domain: failed to lookup DC info for domain
'ADS.CONNON.ME.UK' over rpc

I'm not sure what has triggered this change in behaviour. Authentication
against the domain still works as normal.

I've attached a full debug log of the domain join process.

Anyone got any ideas where I should be looking?

Regards,
Richard