I've critical problem where i using SNMP agent v2 or v1 with store value of Delta (speed per seconds) of simple change
I set update interval of 300 seconds but when I check the Values of graphs i see that 0 or very low speed values which they are fake
after TCPDUMP I see that 2 SNMPget request sent by zabbix server with a few interval like 20ms or 1 sec (regardless of 5min) that caused to 0 speed or 0 change.
why does SNMPGet Request sent Twice ?
also this behavior is randomly repeated and is general for items with SNMP agent and with store value of Delta or simple change
does my server is overloaded ? (my Zabbix Queue size is almost zero or max 10 items with 20 sec delay)
or does this issue maybe related to edge firewall of our network?

pelase see the screen shots
sorry for my bad English but this issue is critical for me