Sometimes encrypted SNMPv3 requests from Network Monitoring Systems (NMS) to devices just fail out of the blue. There is no reasonable explanation for the behaviour. In this article I will describe the problem, spectulate about the reason, and present a workaround (or solution, if you like). It works for me be I am not sure if I really found the real problem. At least it solves the problem which showes some real weired behaviour of the Zabbix server and the monitored device. But the problem not only occures in the Zabbix NMS but I also saw it in the CA's Spectrum system.