Broadband offering speeds of up to 1Gbps is now available to one in four homes across the UK, Ofcom has said.
But 600,000 people in towns and more rural locations remain restricted to 10Mbps or less.
This year has seen increased demand for faster connections, with many people having to work from home.
The government had promised everyone access to broadband speeds of up to 1Gbps by 2025 - but that target has been cut to 85% of homes.
Ofcom network and communications group director Lindsey Fussell said: "For millions of families this year, life during lockdown would have been even more difficult without reliable broadband to work, learn, play and see loved ones."
"So it is encouraging the future-proof 1Gbps broadband is now available to a quarter of homes and we expect that to rise even faster in current months."
The faster speeds are delivered either via:
the enhanced cable network developed for transmitting TV
fibre-optic connections that replace the copper wires installed for the telephone network
Virgin Media offers cable services, while Openreach, a spin-off from BT, has responsibility for the vast majority of fibre-optic connections.
There are also a handful of alternative providers offering bespoke fast-broadband services in various regions of the UK.