Well, assuming wi-fi is not the problem, here's my thoughts, others may differ...
There was a bit of s step improvement in SNRM around about 7am, and a step back about 5pm, which is unusual... a gradual slope between day & night is more common. If you could work out what caused that step, and if you could do anything about it, you might be able to maintain a slightly better connection speed. But it's all a bit irrelevant as connection speed (correct me if I'm wrong) is not what's worrying you, it's the pauses and EXTREME go-slows in throughput. I don't see anything to explain these problems, and therefor I'd attribute them to ISP congestion or traffic management.
As stated, I am also with demon, and I see pretty much the same symptoms that you describe. All is generally OK but in recent months but, if I'm doing a lot of downloads as I am at the moment (experimenting with Linux builds), then every so often - say, several times an hour, things grind almost to a standstill for perhaps a minute or two. I can never prove whether the host websites or demon is the bottleneck, but demon is the common denominator.
It maybe worth noting that demon do have a usage allowance but it's quite generous and, unless you're in the habit of continuously downloading HD movies, I doubt that's the problem. And anyway, a usage cap wouldn't show up as 'intermittent' slow downs.
Given the evidence you've obtained I'm inclined to suggest that demon is the problem. You could complain to them, but they likely try and fob you off. In any case, if their network is chronically congested then they probably already know about it and made a corporate decision not to care about it. You could complain vigorously, and demand that they let you out of any remaining contract period, but they may of course refuse. Realistically, your best bet may simply be to accept any extra cost, and switch to a different ISP. But see my cautions in previous post, it has to be your own decision.
Or does anybody else think differently...?
- 7LM