Loss of Speed with Plusnet router
about 5days ago I set up two M4 decos with a plusnet 2704n router. Before connection router was giving download speeds around 4Mb and upload 1Mb.After the connection, which seemed to go straight forwardly( including firmware update), the speed dropped to 2.6Mb download and 1Mb upload this stayed the same even when hard wired into deco or router. I then disconnected all the decos and checked the router speed it was showing the same as when the decos were attached ( 2.6 and 1 Mb) and has stayed like that for the last 3 days. Anybody got any suggestions?