The delivery of the NBN to Belconnen, inner northern suburbs of Canberra and Civic is now in doubt after NBN Co changed its rollout map on Wednesday.
Those areas had been included as suburbs to receive the high-speed fibre broadband connection within one or three years.
Now all details about future rollouts have been removed from the official map, as NBN rethinks its plans after the Coalition vowed to scale back the national fibre rollout.
In April, NBN Co accelerated plans for Civic, with detailed planning under way and the optic-fibre cable due, at that stage, to be installed by the end of the year.
As well as Civic, the widened footprint for the fast-track work took in Acton and Ainslie.
In addition, several inner-north suburbs had been pushed up the queue and were due to have work begin within a year. They included Aranda, Bruce, Charnwood, Dickson, Kaleen and Lyneham.
The revised rollout map shows Gungahlin and Watson connected, along with West Macgregor, but all the other northside areas due to have fibre installed are now in limbo.
An analysis by the Opposition estimates 5400 households in Belconnen, Bruce, Cook, Macquarie and Aranda could miss out, along with 12,700 in Dickson, O'Connor, Turner, Braddon, Reid, Campbell, Ainsle, City and Acton.
Andrew Leigh, the Labor Member for Fraser, which covers the northside of the ACT, said residents and businesses that were promised the NBN may be left to rely on copper wire for their broadband.
"This is despite the fact that under Labor, north Canberra was scheduled to receive fibre connections in the coming months," he said.
"The Abbott Government should be ramping up the rollout of the NBN, not slowing it down indefinitely.
"Canberrans love very fast broadband – they know it benefits business, schools and households. I'm yet to find a constituent who doesn't want fibre to the home."