I had the following entry appear in the messages file every few seconds
refused smux peer: oid SNMPv2-SMI::enterprises.674.10892.1, descr Systems Management SNMP MIB Plug-in Manager
Based on my research, I found someone who said:
More than likely a Dell machine running OpenManage. Ensure that the following line is in your snmpd.conf if this is the case:
# Allow Systems Management Data Engine SNMP to connect to snmpd using SMUX
I added the above line to /etc/snmp/snmpd.conf file and that resolved the problem.