Virgin Media Ireland says an intermittent fault which impacted hundreds of thousands of its customers here and in the UK yesterday has been resolved.
The issue caused broadband connectivity to drop for a few minutes before returning again and repeated over the course of several hours.
The company said the issue was not caused by increased usage or a lack of capacity, but was down to a technical fault on its network.
It said it recognised how frustrating this was for its customers and apologised for any inconvenience caused.
Customers expressed their frustration with the problem on social media last evening.
The company has 380,000 broadband customers here in Ireland.