A computer-implemented method, comprising: exchanging Auto-Negotiation, AN, Base Pages between a first endpoint device (102, 400, 802) and a second endpoint device (104, 400, 804) in a communication link having a plurality of serially-connected intermediate devices (106, 500) coupled between the first and second endpoint devices forming a serial chain of devices; employing, by the first endpoint device, a first sequence of AN Next Pages to write data to a register in the intermediate device immediately following the first endpoint, wherein the first sequence of AN Next Pages comprises: a first Next Page including a device address of the intermediate device immediately following the first endpoint, a second Next Page including a Management Data Input/Output, MDIO, address corresponding with a register on the intermediate device to which Write data is to be written, and a third Next Page including the data to be written to the register at the MDIO address; forwarding the first sequence of AN Next Pages received by the intermediate device immediately following the first endpoint device to the next intermediate device in the chain, such that the previous intermediate device writes the data to a register of the next serially-connected intermediate device; incrementing and storing the data value called device address for each intermediate device comprising: receiving the device address from a preceding device in the serial chain, incrementing the device address, storing the incremented value as the intermediate device's own device address, and forwarding the intermediate device's device address to the next intermediate device in the chain; and employing a second sequence of AN Next Pages to read the data from the register in each of the intermediate devices. exchanging Auto-Negotiation, AN, Base Pages between a first endpoint device (102, 400, 802) and a second endpoint device (104, 400, 804) in a communication link having a plurality of serially-connected intermediate devices (106, 500) coupled between the first and second endpoint devices forming a serial chain of devices; employing, by the first endpoint device, a first sequence of AN Next Pages to write data to a register in the intermediate device immediately following the first endpoint, wherein the first sequence of AN Next Pages comprises: a first Next Page including a device address of the intermediate device immediately following the first endpoint, a second Next Page including a Management Data Input/Output, MDIO, address corresponding with a register on the intermediate device to which Write data is to be written, and a third Next Page including the data to be written to the register at the MDIO address; a first Next Page including a device address of the intermediate device immediately following the first endpoint, a second Next Page including a Management Data Input/Output, MDIO, address corresponding with a register on the intermediate device to which Write data is to be written, and a third Next Page including the data to be written to the register at the MDIO address; forwarding the first sequence of AN Next Pages received by the intermediate device immediately following the first endpoint device to the next intermediate device in the chain, such that the previous intermediate device writes the data to a register of the next serially-connected intermediate device; incrementing and storing the data value called device address for each intermediate device comprising: receiving the device address from a preceding device in the serial chain, incrementing the device address, storing the incremented value as the intermediate device's own device address, and forwarding the intermediate device's device address to the next intermediate device in the chain; and receiving the device address from a preceding device in the serial chain, incrementing the device address, storing the incremented value as the intermediate device's own device address, and forwarding the intermediate device's device address to the next intermediate device in the chain; and employing a second sequence of AN Next Pages to read the data from the register in each of the intermediate devices.