A physical layer of a first network device is connected to cable of an Ethernet network. A digital signal processor (DSP) is connected to the cable. The DSP receives and decodes first signals on the cable from a second device. The DSP codes and transmits second signals to the second device on the cable. An autonegotiation controller is connected to the DSP and includes a cable detector that determines a first number of pairs of twisted pair wires of the cable that are operable. The autonegotiation controller also includes a speed adjuster that masks an advertised speed of the first device when the cable detector determines that the first number is less than the number required for a requested speed of the first device.