The average UK broadband speed remains less than half that advertised, with regulator Ofcom pushing for new rules to ensure consumers are not misled.
Ofcom's biannual study found the average speed is 6.2Mbit/second, despite the average advertised "up to" speed of 13.8Mbps.
The communications regulator has recommended new rules for advertisers requiring them to cite typical speeds achieved by at least half of customers alongside "up to" speeds, "so consumers have a clearer idea of what speeds to expect", it adds.
It also says a maximum speed should be only be used "if it is actually achievable in practice by a material number of consumers".
Ofcom research indicates consumers would welcome more information on broadband speeds to allow them to make effective and informed choices.
It has passed its recommendations to the Advertising Standards Authority (ASA), which is responsible for any changes to regulations.
The study looked at 11 packages provided by the seven largest internet service providers (ISPs), representing more than 90% of residential broadband subscribers in the UK, compiling results from more than 18 million separate performance tests in 1,700 homes during November and December.
It found next-generation superfast broadband services, available to a growing number of households, were significantly faster than current generation services.
Ofcom's updated code of practice for ISPs comes into force in July, with those who have signed up committed to telling new customers the speed they are likely to achieve at home and to try to resolve problems for those whose speed is significantly below the estimate provided.
If the problem cannot be resolved, customers will be able to leave their provider within the first three months of their contract without penalty.
Ofcom chief executive Ed Richards says: "It is encouraging that new technologies are being rolled out across the UK and faster speeds are being achieved. However, the research shows ISPs need to do more to ensure they are giving customers clear and accurate information about services they provide and the factors that may affect the actual speeds customers receive.
"It is important the rules around broadband advertising change so consumers can make more informed decisions based on the adverts they see, and that advertisers are able to communicate more clearly how their products compare to others in the market."