Openreach - the infrastructure division of BT - is working to repair damage caused to its broadband network by severe winter storms.
The company has declared a status of Matters Beyond Our Reasonable Control (MBORC) across several regions, where telecoms services remain affected.
Engineers are working to restore broadband and phone connections in large areas of the south and west of England, parts of Wales and Northern Ireland and much of Scotland.
With Openreach prioritising network repairs, there may be some delay to the deployment of new connections and other upgrade work.
In a status update, Openreach said much of the UK has been hit by gale force winds, heavy rain and flooding.
"The exceptional conditions resulted in damage to our network, both above and below ground," it added. "As a result, we have seen a major increase in fault intake across the affected areas."
Openreach said it would be monitoring the situation and removing the MBORC status as soon as services can be returned to normal levels.