I'm not sure, why would an SNMP walk from your server across your network to your device fail?
a
FWIIW: we have quite a few few D-Link DGS(Smart) and HP E-series switches (J9xxxA) that die when hit by more than a few HTTP or SNMP-gets/second; or, if the credentials are wrong and it needs to do a syslog() UDP to report such - reproducibly die when the next request arrives prior it having sent the log message.