Just seen your hub stats and power levels look OK. The "RCS Partial Service" errors could be an issue, but as @Rachael_F has carried out checks on the VM back end and found nothing they may have been a temporary glitch.
My setup: V6 TV box, M350 Fibre broadband with Hub 3 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.
We do appreciate all the checks you have done - as our VIP @SCA1972 has advised, I think a new Hub would be the way to go; it sounds like there may be an issue with the ports on the Hub as we've checked everything else.
I'll pop you a Private Message so we can go through security and get one booked out for you.
Just look out for the Purple Envelope and pop us a reply when you can.