We have several SNMP traffic sensors on our firewall and today several of those sensors suddenly produced the following error:
It only seemed to occur with interfaces/traffic sensors for VLANs. Seeing as how the network was still operating normally I guessed there was something wrong on PRTG's end.
The names of the sensors all start with a number like (086) or (120). I tried re-adding the SNMP traffic sensors to the firewall. The new sensors worked fine.
The problem is that we will lose the configuration and historic data of those traffic sensors if we cannot get them to work again. Is there a specific cause for snmp traffic sensors to suddenly give a SNMP_EXECPTION_NOSUCHINSTANCE error? I already asked if someone changed something in the configuration of the firewall, but that did not seem to be the case.