Customers of the Eir phone network and broadband services are experiencing problems this afternoon.
The services has been out for many customers since 12.40 pm.
The Eir website is also down.
Eir has apologised to customers for the inconvenience.
In a statement, the company said: “We are aware of a widespread DNS outage which is impacting some customers on both our fixed and mobile networks. Our engineers are working to correct.”