this problem occurs for me in dude 3.6 as well as the most recent 4.0 beta, I have also recreated it in a smaller instance of the dude monitoring only the afflicted devices
I am using packetflux site monitors for monitoring voltages at remote sites using snmp I have the device label set up to display the snmp values associated with voltage as well as custom data sources for voltage graphs. The problem is that the reported value will often drop to 0 when there is in fact still a consistent voltage. This happens on the label as well as on the data chart. The probe intervals are set to 1 minute with a 2 minute timeout and a 1 minute interval on the data sources I have tried all variety of times for all the settings and none of it seems to make a difference.
Please can anyone help me with this.
EDIT: I have so far been unable to recreate this problem in PRTG Network Monitoring Tool, all values report accurately with 30 second intervals.