Yes, a power cycle was required as mentioned, and the Mac reconnected just fine. Also, the http server for the admin interface was working again.
I started using the dlink NTP server, and so far things are fine. However, the unit should allow selection of LAN-based NTP servers. Since I run one for many systems, I don't need duplicate NTP traffic.
Timezone is correct, and wasn't an issue - the incorrect time could not be accounted for by mere hour or 1/2 hour offsets (as for some DST zones).