Re: The old way@ Rich 11
"I'm still using the cable modem VirginMedia (then Telewest) first gave me more than 15 years ago. I've ignored any offers of a modem upgrade and happily run my own routers off it. I don't know if the old modem is effectively putting a cap on my download speed,"
Depends on your package. I presume you're using a Motorola Surfboard, of which there were several different flavours. From memory the best of them would only achieve 40 Mb/s, and the older ones often a lot slower. If you're receiving and happy with a 20 Mb/s service then there's probably no need to change. If you're on a higher speed (check your bills for the package) just run a Speedtest.net diagnostic and see what it reports. I'd expect VM's routers to be optimised for diagnostics, but for these purposes that's a good thing.
If your download speed is significantly slower than your billed speed, call customer services and ask for an upgrade to a Superhub 2 (they'll probably be very helpful IME, but if asked to, refuse to pay for an upgrade, since you're already paying for the speed and they're not delivering it). Despite the bad publicity, the Superhub 2 is IME a decent fact cable modem, and an adequate if unexceptional wireless router. They usually don't fuss about getting the old modem back, so even if you're not happy with the Superhub 2, you could just reinstate the Surfboard.