Internet users in Kenya, Tanzania, Rwanda and Uganda have been complaining about poor connectivity as service providers across East Africa acknowledge there has been a problem.
They have said they are working to fix it.
The patchy service was a result of faults in the under-sea cables that connect the region to the rest of the world through South Africa, industry expert Ben Roberts told the BBC.
A similar outage was experienced in parts of West and Southern Africa in March.
Cloudflare Radar, which monitors internet connectivity, said that Tanzania was of the worst-affected countries with traffic falling to 30% of expected levels.
Tanzania’s Citizen newspaper described what has happened as an “internet blackout [that] has affected major network channels”.
On X, formerly known as Twitter, service providers have been fielding queries from frustrated customers.
In response to one Kenyan user who wanted to know if they would be able to watch the Manchester United versus Arsenal English Premier League match, Airtel Kenya said its team was working on the “network issue” and apologised.
Safaricom, also in Kenya, said it was “experiencing a challenge”.
Airtel Uganda has said it was aware of the “intermittent internet service”. And MTN Rwanda said there was “an issue of degradation of international links”.
Malawi, Mozambique and Madagascar have also been affected according to Cloudflare Radar.
Mr Roberts, from the pan-Africa company Liquid Intelligent Technologies, said that he had confirmed that one cable that runs alongside the coast of East Africa, known as Eassy, had been cut earlier on Sunday some 45km (28 miles) north of the South African port city of Durban.
Another cable was also cut. He ruled out the idea that it could be sabotage and said it was rather an unhappy coincidence.
Other cables linking East Africa to Europe are also available and gradually the service should improve as data is re-routed.
But as a lot of big companies have data centres in South Africa the damage to the vital link that Eassy provides had a big impact.
In March, widespread outages were reported in countries including South Africa, Nigeria, Ivory Coast, Liberia, Benin, Ghana and Burkina Faso.
This was also put down to cable failures. The cause was not clear but led to the frustration of millions of customers around the continent. BBC.