I did check all cables, replugged them all, I got the no network warning when trying to access internet or get emails on my PC which is connected via Lan cable. I also got no network connection on all my mobile wifi devices. Whenever I rebooted the hub all of the lights eventually came on but the WAN light (double arrow) was blinking sometimes blue, sometimes yellow. I have been out all day and when I returned earlier this evening it was still the same. Rebooted hub and PC again and fault had cleared.
It has been fine for several hours now, thanks for taking the trouble to reply.
Jim.