Customer is asking for additional Ethernet port in RB411U. It will be used for 3G backup with embedded 3G wireless card, so miniPCI-E slot will be full. Is there a miniPCI Ethernet card suitable for Mikrotik?
The solution should be delivered in one enclosure, together with Routerboard and not hanging on some wires beside enclosure.
Purchasing a 433 doesn’t actually add any ports to the 411. I’m sure the OP knows he is allowed to purchase a new device with more ports, that wasn’t the question.
No, use the USB port. The USB port is in the enclosure already. Just consider the usb-to-ethernet to be part of the network cable. This makes is “all in one enclosure”.