Thanks argo & Realalemadrid,
Unfortunatley I did not check which Zen gateways I was on before and after but looking back over each evening I can see the congestion you mention.
Last night however was the first i noticed an impact on everyday use and the graph for last night was the worst I could find.
Recent weeks are seeing congestion in the evenings but if i go back a month
things look ok
Move into August and I start to see
evening graph changes
Nothing compared to
last night.
This will be something I keep an eye on now.
Thanks.