The MAC field's pattern ([0-9/:]+) had no hex letters, so the browser
refused nearly every MAC address (52:54:00🆎cd:ef) and no IPv4 fixed
address could be added from the page. The host name field of both
dialogs ([a-zA-Z0-9_]+) refused names such as web-01 or db.lan. The MAC
takes hex digits and ":", the name letters, digits, "_", "." and "-";
the server already escapes both into the network XML.
