I would like to point out I had similar issues setting up my APC Smart-UPS via SNMP over the network. Tried all the options mentioned and none would work. As a last ditch effort I executed "killall apcupsd" from the console and it worked! I was seeing "apcserver: cannot bind port 3551. ERR=Address already in use" log message in the console so I knew the apcupsd service was hosed up. Even though I was toggling "Start APC UPS daemon" to No and back to Yes. Just make sure you set the first community to public with read access type AND the second community to private with write access type under Configuration > Network > SNMPv1 > Access Control of the UPS. Hope this helps others seeing this behavior. My settings: USB Cable: Ether UPS Type: SNMP Device: 192.168.0.39:161:apc:private - Trent