Thousands of Sky and Virgin Media customers lost their broadband and phone connections overnight after a cable was damaged by workers.
Sky said the issue began shortly before midnight on Wednesday in parts of Hampshire and the Isle of Wight.
It said online services and calls were fully restored by 14:00 GMT.
Virgin Media said the damaged cable had affected neighbouring counties including Dorset, Somerset and Wiltshire.
Responding to customers' tweets, Sky said the problem has been caused by a "fibre-cable break".
In a statement, the company said: "We are aware of an issue with some of our broadband and talk services around Southampton, Portsmouth and the Isle of Wight."
A Sky spokesman said the cable was damaged during engineering work, but could not give the location.
Virgin said the "break" had affected services in areas including Southampton, Portsmouth, Andover, Winchester, Bournemouth, Poole, Salisbury and Yeovil.
It said it was still working to resolve broadband problems.
On its Twitter feed, Virgin Media said a fault affecting mobile phones had been resolved, although it did not give the cause.
The website Downdetector, which measures loss of broadband, said more than 4,000 Virgin customers had reported problems on Wednesday.