Help with EventID 2023 Error value: 1722 The RPC Server is Unavailable during DCPromo to remove Domain Controllers from Domain

Hello,

In a 2008 R2 Forest/Domain, I've tried with a few different Domain Controllers to perform a DCPromo to remove them from the Domain.  The operation fails very early while trying to transfer remaining updates from the Schema partition to another Domain Controller with a RPC Server not available error.  EventID 2023 is generated with Error value 1722.  Below is the text of the error from the DCPromo.

I've tried about 5 times each with 2 different Domain Controllers in different sites and they each contact a different Domain Controller each time I tried and the results are the same in that it fails.

Everything I read points to a replication issue.  With Domain Controllers this operation used to perform the replication, I've performed a manual replication to it successfully.  I dont see any other EventID's errors for this problem as well.

Can anyone plz point me in the right direction to get this resolved?

The operation failed because:
Active Directory Domain Services could not transfer the remaining data in directory partition CN=Schema,CN=Configuration,DC=Fly,DC=By,DC=Nite to
Active Directory Domain Controller BigMamma.Fly.By.Nite."The RPC server is unavailable."

Thanks for your help! SdeDot