This is following on from my upgrade for Exchange 2013 CU6 to CU23 and applying the security patch.
(Non internet facing server) so it was just done recently
The entire upgrade went fine , the cert was out of date but I renewed it and it allowed me to finish upgrade
Exchange server doesnt have any mailboxes databases and is really an Admin console
I believe we would get rid of it ,but have to have it there for MS reasons
Enclosing screenshot of cert error
Googled a few ways to replace this , looking for best way to do this :)
https://www.messaginginsight.com/2017/06/03/setting-or-renewing-a-new-exchange-auth-certificate/