Hello

We are experiencing an issue where SNMP availability is displayed as “Unknown” in the Zabbix frontend for multiple hosts, while SNMP data collection continues normally (items update as expected, no errors).

Observed behavior

• Frontend shows SNMP availability as Unknown for the affected hosts.

• SNMP items keep collecting values successfully (no item errors, data is updated as expected).

Troubleshooting performed

• Confirmed SNMP communication is successful (snmpwalk/snmpget works).

• Reviewed logs and performed packet captures (tcpdump) confirming SNMP traffic.

• Executed snmp_cache_reload (no change).

• Applied OS/proxy tuning recommendations (sysctl adjustments and systemd modifications).

• Ruled out duplicate SNMP EngineIDs (SNMPv3).

• Confirmed item zabbix[host,snmp,available] returns 1 correctly.

• Verified SNMP poller usage on the proxy.

• Increased SNMP pollers on the proxy to 6 (no change).

Best regards,