Data communication

A management device (100) for use in an access network (19,20,30,40,100) including a plurality of data connections between end user devices (10) and an aggregation transceiver device (20) where the connections are aggregated for onward connection through the access network, the device (100) being operable, in respect of each of the connections, to monitor the stability of the connection over at least a first and a second time scale, wherein the monitoring over a first time scale detects a situation in which more than a predetermined number of problematic events occur within a first period and altering one or more parameters of the operation of the data connection in an effort to improve the connection if such a situation is detected, and wherein the monitoring over a second time scale involves monitoring the connection over a longer period and modifying the parameters of operation on an infrequent basis, the infrequent basis having a period between modifications at least an order of magnitude greater than the first period.