It looks like Kyocera have some issues with SNMP implementation on this MFU.
You can check that with snmpwalk:
ifAdminStatus (1 - up, 2 - down, 3 - testing):
nxsnmpwalk -c public TARGET_IP .1.3.6.1.2.1.2.2.1.7
ifOperStatus (1 - up, 2 - down, 3 - testing, 4 - unknown, 5 - dormant, 6 - notPresent, 7 - lowerLayerDown):
nxsnmpwalk -c public TARGET_IP .1.3.6.1.2.1.2.2.1.8