SKY Broadband customers have suffered a loss of service across Essex today.
Sky Talk customers have also been hit by problems caused by "multiple exchange outages".
The company's website said: "Over-running of essential planned network maintenance is causing a loss of broadband and talk services in Essex, including Basildon, Braintree, Chelmsford, Leigh on Sea, Maldon and Southend.
"Our engineers have been on-site since early this morning, carrying out investigation work. They’ve recently confirmed that the problem has been isolated and are working hard to resolve the issue.
"We're sorry for any inconvenience caused."
It is unclear how many people are affected.