Yes, I have had a similar speed drop, but the causes of my problem are unlikely to be the same as yours. So, you've tried a restart of the hub? You've checked that any coax cables in the property are securely terminated, and securing nuts done up finger tight?
JB has asked if this is wifi or cabled because the fault finding goes in different directions depending on the answer. I tend to blame the broadband (VM cable) side of things more readily than wifi, because it seems to me that in about three quarters of cases of sudden speed problems it is a broadband fault - but bear in mind that is a generalisation, and we haven't ruled out a wifi issue.
Can you do the following for me: Connect to the hub by clicking on this link http://192.168.0.1/ That should pull up the log in page for the hub. But don't log in, just click on the link "Check router status" That'll bring up a window with five tabs. Open the Downstream tab. Select all the text (Ctrl-A if using a keyboard), copy it (Ctrl-C), then paste it (Ctrl-V) into a reply here as TEXT not screenshots. Post that, do the same for the Upstream and Network log in subsequent replies. You'll get an error message when you post the Network log, just click on "post" a second time. Then we can check for any obvious problems with power, noise or error counts. If this sounds complicated, don't worry, you're only looking at the status data, there's nothing that can be messed up by accident, just take it one step at a time.
