My parents have an infinity 1 connection which runs at about 34/4.5.
They have an iMac attaced via LAN cable to the HH router and various wireless devices
WHenver they try and upload significant amounts of data (such as photos to my icloud photo library) the whole infinity connection becomes unstable, often disconnecting and reconnecting, with the 'b' on router going red.
As soon as they disable the upload the connection becomes stable again.
I have already unwried the rest of the house from the master socket as I found that plugging it into the primary 'test' port behind the master socket increased the speed of the infiity from 17 to 34.