One in seven homes could be paying more than they need to for broadband and could get faster services for the same or less money, Ofcom has said.
New research suggests that half of UK homes have not taken up faster services even though they are available.
Ofcom has launched a campaign dubbed Boost Your Broadband to let people know about what options are available.
It follows years of effort to ensure that fast internet reaches as much of the country as possible.
A website to accompany the campaign will allow people to check what broadband they can receive in their area, as well as providing independent information on how to get the best deal.
The regulator also announced proposals to force broadband and mobile firms to tell customers about their best available deal, both when their deals are coming to an end, and every year after that if they don't change them.
It also plans to investigate broadband firms' pricing practices to examine why some customers pay more than others.
It is particularly keen to look at introductory offers that run out. It estimates that customers who take a landline and broadband service together are paying an average of 19% more once their discounted deal has expired.
It is currently reviewing how mobile operators charge their customers for handsets when bundled with airtime in a single contract.
Sharon White, chief executive of Ofcom, said: "We're concerned that many loyal broadband customers aren't getting the best deal they could. So we're reviewing broadband pricing practices and ensuring customers get clear, accurate information from their provider about the best deals they offer."
Katie Milligan, a manager at Openreach, which provides much of the UK's broadband network said: "More than 17 million homes and businesses could order a better service over our network today, but haven't yet."
"That means they're missing out on more reliable connections that would allow them to work from home more effectively, access entertainment and use multiple smart devices around the house, all at the same time and without interruption."
She urged consumers to get in touch with their providers to find out what deals they could get.
Ofcom's findings are borne out by earlier research carried out by price comparison service uSwitch, which found that more than a third of those living on streets with slow broadband had access to much faster services.
Richard Neudegg, head of regulation at uSwitch welcomed Ofcom's plans to intervene.
"Historically in telecoms, not enough has been done to put the power back into consumers' hands. If customers are given the right tools, there is a real chance to improve households' experience of services that are now critical in their day-to-day lives."
"As our slowest street data brought to life, consumers are getting very different outcomes from the broadband market - and in many cases, this is simply due to a lack of awareness about the better services available to them."
Matthew Howett, founder of research firm Assembly, thinks the reason many do not upgrade is a combination of apathy and contentment with the service they have.
"I think fundamentally most households are generally satisfied with the speeds they are getting, and find their needs are met although, of course, this changes when you introduce larger families, multiple streams of HDTV, and online gaming.
"All of these more bandwidth-intense services will push up a household's requirements. The other thing to consider is the complexity faced when choosing a broadband package.
"While there are many good tools to help consumers shop around for the best deal, different contract durations, introductory tariffs, and added extras make changing package or supplier a daunting prospect for some."