I think this will be my final update on this. Today I did a fresh install into a KVM instead of LXC container. This time I had to follow the install directions on the website much closer because the KVM is like a bare-metal install and had SELinux enabled. However, this install did NOT have the hostname issues, and I didn't need to change the localhost references to 127.0.0.1. I think that problem is unique to LXC containers.
I still had to apply the T967 fix to get rid of the 30 second error messages in Roundcube.
For iRony, I also had to manually apply T1022, as outlined here: https://kolab.org/hub/topic/15/upgrading-kolab-3-4-to-16/13. I've been able to download content using DAV, but I've not been able to do a two-way sync. Don't know if that's my client or iRony. Basically I'm seeing this at the client when trying to send data:
"CalDavSynchronizer.DataAccess.WebDavClientException: Response status code does not indicate success: '500' ('InternalServerError'). Message:
<?xml version="1.0" encoding="utf-8"?>
<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
<s:message>Storage error. Library not found.</s:message>