We experienced an issue today where an expired SSL certificate was being used on one of our load balanced web servers. This was causing intermittent certificate expiration messages for end users.
We monitor all load balanced web servers for expiring certificates, however we found today that one of the servers had an unused configuration section that was somehow being referenced when requesting the certificate for that server.
By removing this unused configuration, the server started referencing the correct certificate from the correct configuration.
Because we removed the unused configuration, this is not an issue we expect to happen again at the next certificate renewal date (in 2022).