похоже, в версии 3.5.90 не работает snmpv3.

config attachef, результат poll:
[13.10.2020 11:29:10] Capability reset
[13.10.2020 11:29:10] Checking node's capabilities...
[13.10.2020 11:29:10]    Checking NetXMS agent...
[13.10.2020 11:29:15]    Cannot connect to NetXMS agent (Connect failed)
[13.10.2020 11:29:15]    Checking SNMP...
[13.10.2020 11:29:15]    Checking EtherNet/IP...
[13.10.2020 11:29:20]    Cannot get device identity via EtherNet/IP (CONNECT FAILED)
[13.10.2020 11:29:20] Capability check finished
[13.10.2020 11:29:20] Checking interface configuration...
[13.10.2020 11:29:20] Unable to get interface list from node
[13.10.2020 11:29:20]    Interface "unknown" is no longer exist
[13.10.2020 11:29:20] Interface configuration check finished
[13.10.2020 11:29:20] Checking node name
[13.10.2020 11:29:20] Node name cannot be interpreted as valid IP address
[13.10.2020 11:29:20] Updating general system hardware information
[13.10.2020 11:29:20] Finished configuration poll for node SW53-2530-8-PoE
[13.10.2020 11:29:20] Node configuration was not changed after poll
[13.10.2020 11:29:20] **** Poll completed successfully ****

при тех же настройках SNMP tester (Paessler) спокойно опрашивает switch.
если использовать версию 2c - poll без проблем.

switch, с которым игрался - aruba 2530.