After connection and speed trouble in the past week the helpdesk booked an engineer to come out and swap out the SuperHub 2 router for a new HUB 3.0. The engineer was brief and said that the power db was too high and fitted a 3db and 10db attenuators.
But nothing improved, in fact if possible it has got worse! Speed test is hit and miss sometime 20MB but most less than 10MB and more often less than 1MB with lots of disconnects. Nowhere near the 70MB advertised number.
I have now set the HUB 3.0 into modem mode and dug out my Fritz box and at least I have some stability now. But the speed issue remains.