Well, could be a local equipment problem, and you'll have to hope for that, because its the only thing that might be fixed!
In circumstances of "over-utilisation", which initially looks much like your BQM, fixing the problem does often take years (cost, planning, access, technical limits assuming VM indeed will spend the money), but looking at your BQM I'm not sure it is so simple. Things may not be ideal, but they calm down markedly after 6pm, more so after 10pm. So what this suggests to me is that the problem is indeed an excess of home workers, putting too much load on the local network. Note that shop, factory, road workers can't work from home, so the impact of more home working is very localised - if you live in a nice area of detached houses (like I do) then you'll see more of this. But when us keyboard warriors log off the corporate VPN, things get better.
Now, even after 10pm things on your BQM aren't perfect, and what that suggests to me is that your local network is (under ordinary circumstances) fully subscribed, and just coping. Realistically, VM won't invest to increase capacity due to capacity problems under Covid, so nothing is going to change soon. And even when the office-bound masses (people like me) return to work, you'll probably still see that dodgy post 10pm performance. If that's the case, then you need to choose between VM's bandwidth ("speed") and Openreach's latency. Here's a link to a BQM for an elderly relative's Openreach connection that I keep an eye on. And that beauty is costing £35 a month. Pity they aren't a gamer, eh?
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