The Uptime Infrastructure Monitor Net-SNMP agent type is intended for server platforms (How to add a Net-SNMP enabled server to Uptime Infrastructure Monitor).  Most network devices (e.g. switches, routers, firewalls, etc.) do not have the full set of required MIB information and should be added as Network Device elements.
Uptime Infrastructure Monitor depends on the following MIBs for the Net-SNMP type:

To test if your device is hosting these MIBs, use the snmpwalk command from any Linux server or an SNMP browsing utility on your desktop to attempt browsing the OIDs listed above.  Here are some examples using snmpwalk from the command line:

# snmpwalk -v 2c -c <community string> <hostname> .1.3.6.1.2.1
# snmpwalk -v 2c -c <community string> <hostname> .1.3.6.1.2.2021
# snmpwalk -v 2c -c <community string> <hostname> .1.3.6.1.2.25