This powerful NAS (linux core inside) have 2 NICs that you can use in various mode.
I’ve choose to  aggregate these 2 NICs to have load balance and failover.
Through the web page go to System administration, then to network; here flag “Enable port trunking” option.
in the dropdown menu ou have to choose “IEEE 802.3ad”. and apply settings.

Let’s go to the cisco switch ( I have Cisco IOS, not CAT OS)
i’m assuming the two NICs are connectet to Gi1/1 and Gi1/2 (adapt to you)

interface GigabitEthernet1/1
 description to NAS
 switchport access vlan 10
 switchport mode access
 speed 1000
 duplex full
 channel-protocol lacp
 channel-group 64 mode active
end

interface GigabitEthernet1/2
 description to NAS
 switchport access vlan 10
 switchport mode access
 speed 1000
 duplex full
 channel-protocol lacp
 channel-group 64 mode active
end

interface Port-channel64
 description Connessione NAS
 switchport
 switchport access vlan 10
 switchport mode access
end

With this configuration on the switch, when you disconnect one NIC you will not loose connection to the NAS even if you are transferring data.