It is not just rural areas which are suffering from slow broadband speeds, Ofcom has claimed.
In its latest report, the communications regulator said connectivity issues are also affecting UK towns and cities.
Average UK download speeds may have reached 31.9Mb in November 2013, but Ofcom reports not all households and businesses are benefiting from next-generation technology.
It will be publishing research into the "important issue" of urban broadband variability later in 2014, with a view to tackling the problem.
Ofcom is seeking to explore with operators any barriers to the roll out of higher-speed services in urban areas.
Much of the funding set aside for network upgrades by the government is being used to improve the reach of super-fast broadband in the countryside.
However, the Con-Lib coalition has also launched a voucher scheme, designed to help businesses in under-served urban areas improve their connectivity.
Companies across 22 UK cities can apply for vouchers worth up to £3,000, as they aim to boost the quality of their internet service.