Hi,

Issue Description: We are deploying a new tool for monitoring called Zabbix, when we deploy Zabbix server to monitor our network devices using SNMP v3 we get timeout getting data from the devices as seen in below logs:

13345:20190724:091038.222 SNMP agent item "system.cpu.utilv3c1[cpmCPUTotal5minRev.\{#SNMPINDEX}]" on host "XXXXX-XXXXX" failed: first network error, wait for 15 seconds

13314:20190724:091039.231 SNMP agent item "system.cpu.utilv3c1[cpmCPUTotal5minRev.\{#SNMPINDEX}]" on host "XXXXX-XXXXX" failed: first network error, wait for 15 seconds

Cannot find module (BLUECOAT-SG-DISK-MIB): At line 0 in (none)

13310:20190724:091041.518 SNMP agent item "system.cpu.utilv3c1[cpmCPUTotal5minRev.\{#SNMPINDEX}]" on host "XXXXX-XXXXX" failed: first network error, wait for 15 seconds

As a result of these timeouts, we are unable to populate proper graphs with accurate data.

 We are using SNMP v3 with AuthPriv set up. 

When we change to SNMP v 2c or SNMP v3 with AuthNOpriv we do not encounter this issue.

We have increased the zabbix timeout in server.conf to maximum allowed value of 30 seconds. However, the issue still persists. 

The device happens with various vendors including CISCO and Checkpoint.

We need a fix as this is as it is holding deployment and it seems like a bug or limitation at Zabbix code level.