The creator of the web says coronavirus has highlighted the importance of internet connectivity as a basic right.
Sir Tim Berners-Lee says too many young people do not have internet access and the digital divide has widened during the pandemic.
He called on governments to invest to provide universal broadband by 2030.
"We can't afford not to do it," he wrote in his annual letter to mark the anniversary of the world wide web.
'A lifeline'
Sir Tim first conceived of the web while working at the Cern particle research lab in 1989.
He says over the last 12 months, it "has proven to be a lifeline that allows us to adapt and carry on".
But, he says, one-third of young people do not have any internet access and many more lack the quality of connection needed to work or learn from home.
In an interview with the BBC, he said that as the web became more powerful, the digital divide between the haves and have-nots had grown wider.
"That's always been the case," he says.
"Now working from home, and learning at home, have made it much more clear."
He says this applies in the UK as well as in developing countries.
"The UK cannot be complacent," he says.
"A shocking number of kids in the UK don't have meaningful connectivity."
The computer scientist is calling for an acceleration of the push to bring fibre broadband and better mobile connections to rural areas.
"It should be a much higher priority of both businesses and government," he says of his home country.
On Tuesday, the Secretary of State for Digital, Oliver Dowden, said the government was working "tirelessly" with broadband companies to extend access to hyperfast broadband.
"Two years ago, we were about 7% [of premises with] gigabit-capable broadband. We're now up to about 30%, and I'm confident by the end of the year that we'll get to 50%.
"I will be prioritising the hardest-to-reach places, and we will be setting out a broadband action plan in about a month or so."
Misinformation and abuse
Sir Tim's letter, written with the co-founder of the Web Foundation Rosemary Leith, calls for a global push to connect young people.
It quotes a figure of $428bn (£306bn), which the Alliance for Affordable Internet initiative says would need to be invested by governments and the private sector to achieve this aim by 2030.
But, the letter says, this would deliver huge economic benefits for the developing world and concludes "we cannot afford not to do it".
Sir Tim also expresses concern about misinformation and abuse on the web, particularly that aimed at young women.
But he says the pandemic has offered the opportunity to think again about improving his creation for everyone.
"There's a very positive energy about people fixing things, and building a better world," he says.