The UPS support is very unfortunate and not working for me at all.
I have the APC Back-UPS ES BE550 (one of the 3 officially supported UPS models) and my testing with the NAS behaviour with this UPS yielded the following results:
Got it working. In short, the problem seems to be rooted in 2 things:
1) Mandatory clause of at least 1 monitored UPS missing in /usr/local/ups/etc/upsmon.conf
(see "UPS DEFINITIONS" in
http://www.networkupstools.org/docs/man/upsmon.html)
2)
upsmon daemon - UPS monitor and shutdown controller - not running (will not start due to config error in 1)
To remedy, command-line access is needed. For me the fonz fun-plug worked.
What I did was simply to add the following lines at the end of Volume_1/fun_plug script:
echo "MONITOR usbhid 1 root 123 master" >> /usr/local/ups/etc/upsmon.conf
upsmon
Basically, D-Link could have defined all 4 possible upses (usbhid, bcmxcp, megatec and tripplite as set in /usr/local/ups/etc/ups.conf) to be monitored on, here.