Unwanted/Generic Devices

Newish installation. Windows Server 2012. My Configure/Update inventories look pretty good. However, my Monitor views are terrible. Monitor>Inventory has a few dozen devices that don't belong. Sonicwalls, Cisco switches, etc. Monitor>Events is even worse. I'm getting spammed with minor SNMP alarms and other errors from non-Cambium non-managed devices on the network. How do I deal with this?