Okay, this was an easy fix. I had two subdomains that in the list that were causing the renewal process to bomb out due to missing DNS entries. Fixed and all good.
i.e. DNS entries were in place for
DOMAINNAME.com and WWW.DOMAINNAME.COM
but not for:
AMDIN.DOMAINNAME.com or WEBMAIL.DOMAINNAME.com
and this was causing the auto-renewal to error out. I realize that I initially had DNS entries for all of these, but had removed ADMIN and WEBMAIL from my DNS entries on this specific virtual sub-server (AKA TLD name).
I think it’s the reference to the :10000 and :20000 ports that makes this seem more than it really is, at least that was the case for my issue. Your mileage and experience(s) may vary.
Hope the elaboration helps the next guy.