The command set system inband enable true is obsolete and replaced by command set system inband vlan-interface <vlan-interface>.
By default, the user cannot remotely log in and manage the switch through an L3 VLAN interface. You need to enable the in-band management function by setting set system inband vlan-interface <vlan-interface> to perform the SSH, TELNET, SNMP and HTTP services through any one of the L3 VLAN interfaces in the default VRF.
Set the L3 VLAN interface VLAN400 in the default VRF as the in-band management port.
In-band management provides a method of access to the switch even if the Ethernet0/1 interface is down.