First switch the Hub off for 5 minutes AND unplug it from the mains. Whilst it's off, do a quick check that all of your coax cable connections are in nice and "finger" tight - at the Hub and wall box and also at any connectors etc. Ensure there are no “unterminated cable loose ends. Disconnect all the connections and reconnect them just to be sure. Also check that the internal wiring is ok with no kinking or chaffing, check that all looks good with the outside cabling and wall box. Then switch it on again and leave 5 minutes to settle.
Then do a Hub “pinhole reset” - but, make sure the 2 passwords on the Hub sticker are still there and legible first ! Disconnect any ethernet cables from the Hub, and then with the Hub still "switched on" throughout, press the reset pin on the back in firmly with paper clip/SIM tray tool or similar "thin thing" and hold it there firmly for 60 seconds – release the pin then leave the Hub 5’ to stabilise then see if the issue still persists.
If it does, post up your Hub/network connection details and someone will check to see if there is a problem there. In your browser’s URL box type in http://192.168.0.1 (or http://192.168.100.1 - if in modem mode) and hit return. On the first page up [there should be no need to login if you have done so before unless you have the New Hub4 when you do] click on the “router status” icon at top right (if you have an SH1/2) or the text at bottom-middle of first page up (on a Hub3) and then "copy/paste" as “Formatted Text” (not images) 3 FULL sets of data onto here – the 2 pages from the Downstream tab,the 2 from the Upstream tab, & also the Network Logs page. Don't worry too much about the formatting it can be easily read & DON’T include personal data or MAC addresses - blank them out - if you copy/paste the data, the board software will do this for you (you may need to click the "submit" button again). You may have to do separate posts - but that's fine.
Also, in the meantime... if you haven’t already, set up a free “Broadband Quality Monitor” to continually monitor the state of your connection and record any true network dropouts , latency issues, packet drops, etc - it will thus allow you to differentiate between those and simple wifi dropouts. It does it 24/7/365 and it keeps a visual record of any/all of your network disconnections, useful data to have to match to the Network logs (in your Hub settings) and also in discussions with VM - note it will take a few hours to start seeing a sensible picture - post up the “link” (as per instructions on the TB website) when you have the first 24h period.
Just go here and follow the instructions on how to set it up and get a "link" - its easy and safe/secure.