Ethernet link lights on router not lighting up

I bought a used Brother MFC-9140CDN. It's in amazing condition and hasn't even printed 4000 pages yet. However, there seems to be a problem when connecting the printer to my router via ethernet cable. The link lights do not light up, no matter what I do - changing cables, ports, and the cable even passed the loopback test, so there's no doubt that the cable and the ports on the router are working. What should I do? Could the network card or the port on the printer be the problem? That is the only way I can connect the printer to the network, since it doesn't come with Wi-Fi.

Also, the network config print says that Brother Online Con is disabled, IP Filter is disabled, the WIRED IEE 802.1x Status is off, and the Ethernet Link Status is Link DOWN, 10baseT #Link drops=0, and all the Network Statistics are all set to 0.