Which USB port do I use to upgrade firmware?

Most iConnectivity interfaces have more than one USB port. However you can only use one of these ports to perform a firmware upgrade. This list shows which port on each interface that can be used to upgrade that firmware: 

mio2 - USB Device Port 2(front)

mio4 - USB Device Port 2 (back)

mio10 -USB Device Port 1 (back)

MIDI2+ - USB Device Port 2 (front)

MIDI4+ - USB Device Port 3 (back)

ConnectAUDIO2|4 - USB Device Port 1(back)

AUDIO2+ - USB Device Port 1 "power"( back)

AUDIO4+ - USB Device Port 1 

PlayAUDIO12 - USB Device Jack 1 (front)

PlayAUDIO1U - USB DAW A (front)