The following works for setting the snmpv3 configuration on cambium 450i 900’s. Once applied it’ll run change the SNMP settings and reboot the radio.

You’ll need to find the hashed password which can be found in a config backup.
Change the SNMP username/community as needed.

{
     "userParameters": {
         "snmpConfig": {
             "user2Group": 0,
             "snmpv3EngineId": "007000a9840a003e464e7a",
             "rwAuthPasswordEncrypted": "3e5h24a694a515e81abb6b25986cea91",
             "commStringROnly": "rocommunitystring2",
             "user2PrivPassword": "",
             "user1AuthPassword": "",
             "snmpv3AuthProt": 0,
             "snmpv3TrapEnable": 0,
             "snmpv3PrivProt": 0,
             "snmpMibPerm": 1,
             "roAuthPasswordEncrypted": "3e5h24a694a515e81abb6b25986cea91",
             "commStringRW": "communitystring",
             "userGroup1": 0,
             "user1Enable": 0,
             "snmpv3SecLvl": 2,
             "user2Enable": 0,
             "rwUserName": "Canopy",
             "roUserName": "snmpv3user",
             "roPrivPasswordEncrypted": "3e5h24a694a515e81abb6b25986cea91",
             "userName1": "",
             "snmpPort": 161,
             "rwUserEnable": 0,
             "trapDomainNameAppend": 0,
             "rwPrivPasswordEncrypted": "3e5h24a694a515e81abb6b25986cea91",
             "user1PrivPassword": "",
             "userName2": "",
             "user3PrivPassword": "",
             "user2AuthPassword": "",
             "userName3": "",
             "user3Enable": 0,
             "snmpTrapPort": 162,
             "user3AuthPassword": "",
             "user3Group": 0,
             "trapDelayAfterBootup": 5,
             "snmpIpAccessFilter": [
                 {
                     "address": "192.168.0.0",
                     "netmask": 24
                 },
                 {
                     "address": "10.0.1.0",
                     "netmask": 24
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 },
                 {
                     "address": "0.0.0.0",
                     "netmask": 0
                 }
             ],
             "snmpTrapAddresses": [
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0",
                 "0.0.0.0"
             ]
         },
 }