Virgin Media users have complained of repeated internet outages, accusing the network of making working at home impossible.
Social media users have written to the provider saying they have suffered days of sporadic cuts to their broadband service.
The Downdetector website has recorded complaints across the UK, particularly in areas around London and Birmingham.
However, a Virgin Media spokesperson told the Standard it was a "localised issue" in the south of the capital, affecting a "very small number of customers".
It comes a month after major problems were reported with the provider's broadband and TV services, with hundreds of customers venting their frustrations.
One Twitter user said on Tuesday morning: “For the second time in a week I have no TV and no internet. I live in the Tamworth area, will this issue be resolved soon? I am unsuccessfully trying to work from home.”
Another tweeted: “I'm getting sick and tired of connection dropping randomly for 1-5 minutes. I've done all the normal troubleshooting steps and they've not helped.”
Another commented: “Another day, another day of no internet access from Virgin Media. Oh, and no phone service either. #stayconnected rings very hollow.”
And another said: “What's happening with your internet and TV services again?
“All my stuff’s down but once again I'm not alone. What are you doing to rectify this and why haven't you informed me your services are affected?”
The spokesperson for Virgin Media insisted the issue had not been widespread, but affected "a small number of our customers in the Lambeth area."
They acknowledged it had caused problems with broadband, video on-demand and some telephone services.
In an update at around 1pm they said: "We have fixed an issue which affected services for a very small number of customers in the Lambeth area and we apologise for any inconvenience caused.”
