Thank you @nckrwlmn. Your first paragraph is why I didn’t uninstall.
I just have the basic logs available at present; after looking through them (they aren’t available in one of the available file types to upload), the only repeated error was: “Failed to send email. (Failed to execute request curl_easy_perform error: 6).”
The network config is below.
I couldn’t find any suffix setting for my (kea) DHCP server; I’m using only its default settings. However, under Control Panel | Network setings | General | Advanced Settings the “Apply the domain name provided by the DHCP server” is unchecked. I unchecked it to fix multiple “Erred” DNS queries (see this topic).