A second unit of a system comprising a first unit communicatively coupled to the second unit via a communication link, the second unit comprising: a reconfigurable circuit, wherein a first circuit configuration image and a second circuit configuration image are stored in the second unit, wherein the reconfigurable circuit is configured with either the first circuit configuration image or the second circuit configuration image; an interface device configured to communicatively couple the second unit to a communication link with the first unit, wherein a first interface configuration image and a second interface configuration image are stored in the second unit, characterized in that: wherein the interface device is configured with either the first interface configuration image or the second interface configuration image based on the configuration of the reconfigurable circuit; wherein the second unit is configured so that the interface device is configured with the first interface configuration image in response to the reconfigurable circuit being configured with the first circuit configuration image; and wherein the second unit is configured so that the interface device is configured with the second interface configuration image in response to the reconfigurable circuit being configured with the second circuit configuration image; wherein the second unit is configured to automatically revert to the first interface configuration image if the interface device is not able to be successfully configured by the second interface configuration image, wherein the second unit is a remote unit of a distributed antenna system, DAS, wherein the reconfigurable circuit is a field-programmable gate array, FPGA, wherein the first circuit configuration image is a first FPGA image, wherein the second circuit configuration image is a second FPGA image, wherein the interface device is a physical layer, PHY, device, wherein the first interface configuration image is a first PHY image, wherein the second interface configuration image is a second PHY image. a reconfigurable circuit, wherein a first circuit configuration image and a second circuit configuration image are stored in the second unit, wherein the reconfigurable circuit is configured with either the first circuit configuration image or the second circuit configuration image; an interface device configured to communicatively couple the second unit to a communication link with the first unit, wherein a first interface configuration image and a second interface configuration image are stored in the second unit, characterized in that: wherein the interface device is configured with either the first interface configuration image or the second interface configuration image based on the configuration of the reconfigurable circuit; wherein the second unit is configured so that the interface device is configured with the first interface configuration image in response to the reconfigurable circuit being configured with the first circuit configuration image; and wherein the second unit is configured so that the interface device is configured with the second interface configuration image in response to the reconfigurable circuit being configured with the second circuit configuration image; wherein the second unit is configured to automatically revert to the first interface configuration image if the interface device is not able to be successfully configured by the second interface configuration image, wherein the second unit is a remote unit of a distributed antenna system, DAS, wherein the reconfigurable circuit is a field-programmable gate array, FPGA, wherein the first circuit configuration image is a first FPGA image, wherein the second circuit configuration image is a second FPGA image, wherein the interface device is a physical layer, PHY, device, wherein the first interface configuration image is a first PHY image, wherein the second interface configuration image is a second PHY image. wherein the interface device is configured with either the first interface configuration image or the second interface configuration image based on the configuration of the reconfigurable circuit; wherein the second unit is configured so that the interface device is configured with the first interface configuration image in response to the reconfigurable circuit being configured with the first circuit configuration image; and wherein the second unit is configured so that the interface device is configured with the second interface configuration image in response to the reconfigurable circuit being configured with the second circuit configuration image; wherein the second unit is configured to automatically revert to the first interface configuration image if the interface device is not able to be successfully configured by the second interface configuration image, wherein the second unit is a remote unit of a distributed antenna system, DAS, wherein the reconfigurable circuit is a field-programmable gate array, FPGA, wherein the first circuit configuration image is a first FPGA image, wherein the second circuit configuration image is a second FPGA image, wherein the interface device is a physical layer, PHY, device, wherein the first interface configuration image is a first PHY image, wherein the second interface configuration image is a second PHY image.