While most of Gungahlin has been wired for superfast NBN, one part of Casey was forgotten.

Now residents on the west side of Ashton Calvert Street can download videos at high speed, but just a few metres away, it's a different story.

On the east side of the street, residents struggle with internet access over the dodgy copper wire network that was installed when the suburb was built.

"That area, for some reason, didn't get the telecoms rolled out by TransACT, didn't get fibre to the home and got standard Telstra copper grade services connected to the homes in that area," Mr Elford said.

Residents who missed out on the superior internet had been complaining bitterly for some time, he said.

"There was some oversight or misunderstanding," he said.

"I've been assured that the fact that Casey stage one needs to have the NBN delivered to it has been acknowledged by NBNCo and they are going to do something about it.

"They haven't indicated whether they will build fibre to the premises, which by the way every single house around them has, or whether they will get the fibre to the node."

Gungahlin was granted early access to the NBN by the federal Labor government because of the inferior telecommunications infrastructure installed when the suburb was built.

Residents were given fibre-optic cable to the home, which delivers internet at faster speeds than fibre to the node – a cabinet in the street – the system adopted by the Coalition government.

Andrew Leigh, the Member for Fraser which includes Gungahlin, said the NBN blackspot in Casey was concerning.

"It's one of those situations where you've got one side of the street connected, and the other side of the street not," he said.

"It's particularly frustrating for people where they live across the street from someone who has the NBN.

"They can't see any logical reason why one side of the street should be connected and the other side shouldn't.

"It's unfair to be leaving one side of the street back in the 19th century while the other side of the street streaks ahead in the 21st."

While the street in Casey is a case of digital envy, an even bigger digital divide exists in the ACT, with the south missing out, according to Gai Brodtmann, the Member for Canberra.

"We've got suburbs like Monash and Theodore, which have the lowest rating in the country for availability and quality of broadband. They're still not on the rollout map," she said.

"We have a digital divide now in Canberra.

"[Minister for Communications] Malcolm Turnbull promised that every home and business would have access to 25 megabits per second by the end of 2016, and he's failed to make that happen.

"In Gowrie, they are getting 1.3 megabits per second, Kambah 2.2, Wanniassa 1.7, Banks 1.5, Monash five to six, Calwell0.5, Bonython 0.8 and Duffy, 1.25.

"He also promised that parts of Australia that had poor internet access would get the NBN first."

Ms Brodtmann is gathering signatures on a petition to go to Mr Turnbull, asking for the southside to have NBN priority.

Liberal senator Zed Seselja points out the network is well under way in the ACT, with more than 31,000 premises currently passed, another 14,000 under construction and more than 56,000 premises to start construction in the ACT during the next 18 months.

"We have doubled the NBN footprint since the election and are looking to more than double it again in the next 18 months," he said.