Okay so when we first got Virgin media internet in the speeds were perfect. Now it's difficult to reach 3mb/s download speed at night with it usually peaking at 20mb/s in the afternoon. This is with the 100mb/s package. I've tried restarting the router which does nothing and sometimes stops the internet from working all together for around 15 minutes. One strange thing is that upload speed always seems to be relatively fine at around 6mb/s. It is just really frustrating especially considering i've been putting up with this issue for months now hoping that it would fix itself.
Your downstream power levels are way too low and the downstream SNR is out of spec.
If you have a barrel shaped attenuator screwed to the coax at the back of the hub you could try removing it but i doubt if it will completely resolve the problem.
With your downstream power levels so low it would be hard to say if the evening slowdown will be down to contention or the instability of your connection. VM will be able to check when they pick up the thread.
You will need to contact VM for resolution, either by waiting here about a week until a VM Forum Team Member picks up the thread, or give them a call on 150 from a VM line or 0345 454 1111 for a quicker response.
I looked at what you said about a cylinder plugged in at the back of my router and removed something that said equaliser on it. Anyway my speeds have increased from 3mb/s to 65mb/s. 95mb/s on my wireless. I don't know if this fix will work for ever but for now it is. So yeah.