SNMPv3 Cisco route switch SNMP agent availability not available (0)

[jjsomm]

I have a customer that we have moved to SNMPv3. The issue I am having are Cisco Routers and switches show SNMP agent availability - not available (0).
If I reboot the proxy they will show available at first and, then they start dropping off.

I still get all other data from the devices and Zabbix never reports them being down.

One thing I did notice are devices that are classer to the proxy have less issue. Also when I was on SNMPv2 I did not have any issues.

Currently running Zabbix 4.4. Looking to upgrade but we monitor several proxies and it is all running on CentOS 7 so, upgrading is going to be quite a task.

Any ideas on my issue?

[Rudlafik]

Hi, I have the same problem on Cisco on cheap switches. On CISCO ASA, everything is fine when using SNMPv3. Also the HPE and SNMPv3 servers on our ZBX 5.4.8 are OK. However, it is interesting behavior when querying OID from different MiB according to RFC. Of course, everything is fine on SNMPv2 and everything will load. According to CISCO, the RFC of some MiB libraries is poorly implemented. For some SNMPv3 OID queries, you will not get an answer for some. I combined different levels of authPriv security and nowhere did I find a working way to apply functional SNMPv3 to CISCA's soho products. After consulting with LAN / WAN product professionals, I came to the conclusion that CISCO branded another company's product and emulated - strangely - its IOS in its Linux OS. Just another waste from CISCO. We are now disposing of these switches and buying active components from HPE and Fortigate. They are cheaper in price, performance in the same way as CISCO and at least comply with RFC standards. Before the HPE arrives, the "waste" CISCO goes to SNMPv2.