AD Takeover, Or as AD Backup DC Errors

Hi Guys,

Current Setup windows server 2016 / Forest and Domain level windows 2008

Domain name:
Server pdc

i have previously installed ucs server as a backup dc, for some reason or another i deleted it, and now when i try to add ucs as a backup dc i get the error
“the connection to ucs dc master was refused,please recheck password”.

i have removed the previous dns record from windows dc, but still i get the error. i can connect windows pcs to windows dc no issues with admin pass.

Please help

I know this is 3 yrs old, but I have the same issue and no one answered here?