I have a pair of Zyxel PLA4201 powerline adapters bridging our Virgin Super Hub in one room upstairs (where the Virgin broadband wall socket is located) to a second wifi router downstairs acting as a secondary access point. If I connect to the wifi downstairs I sometimes get excellent performance but it doesn't last long, slowing down to a crawl frequently, sometimes failing altogether and then a few minutes later it's back to normal for a while. The wireline connection status light is usually normal (green) downstairs but red or orange upstairs. It's never green upstairs.Both Zyxel units are plugged directly into wall sockets and I have experimented with different sockets for the downstairs one but without much benefit between one another. The unreliability experienced seems random, no particular time of day and no electrical items in our house seem to be switching on to cause the problem. If anyone has any suggestions for solving this problem I would be most grateful!