[Samba] DRS stopped working after upgrade from debian Jessie to Stretch

[Rowland Penny]

Before you go down the 'backup' line, you mentioned that you have three
DCs, is only one DC giving problems or all three ?

If it is just one and the other two are working okay, I would demote
the faulty DC and remove it from the domain. I would then check the
ex-DC for faults (the HD for instance), once you are sure that there
are no faults or you have fixed any ones found, you can then rejoin
it as a DC (I would change its hostname as well).

Rowland