You may lose the customer's Solr and smtp info if you don't do this.
The information is located in the DAM Center → System tools → Digizuite Configuration = search for "SMTP" and "Solr" and take a snip of the result - paste it into a document (just in case...)
Please note down all the solr and smtp configurations (Constants in DC only) from the DC installation - as we've experienced IHP having these deleted upon the update.
It of course worked before the update. PSU and Leon's environments didn't experience the same issue.