We have had this problem in our house since August 2016 throughout the day our internet speed will just drop dramatically making it completely unusable I've seen my download speeds drop to 0.01 while doing a speed test, this will be a issue for 4 - 5 hours in a day then it will go back to normal.
This is across all devices in the house some wired some wireless, while this is happened rebooting the router doesn't make a difference also resetting the router to default settings also has no effect.
This is the results I get from think broadband if this helps
I have attached more screenshots below I am not sure
And some other screenshots not sure if these help at
I am truly sorry about your recent (ish) speed dips. Tests of your connection do reveal a peak time speed fault, ref: F004243156, for which a network upgrade is planned.
However that wouldn't account for the packet loss indicated in your BQM (thanks for posting that by the way).
So the first thing I'd like to address is that of the slightly elevated downstream power levels on your Hub. I have sent you a PM (purple envelope icon, top right of page) so that we can make arrangements for an engineer visit. I shall get this booked in as soon as I receive your reply and we'll take things from there.