The websites of HSBC, ITV and Waitrose were among those affected by a widespread outage that caused a brief outage Thursday afternoon.
The main online banking services, including Barclays, TSB, Bank of Scotland, Tesco Bank and Sainsbury’s Bank, were totally or partially inaccessible for a short period.
Airbnb, PlayStation Network, and Steam also experienced the temporary glitch, with some showing users a DNS bug.
Unconfirmed reports suggest that the issue may be related to a performance product offered by Akamai, an American company, which began investigating the issues shortly after 5pm UK time.
Its Edge DNS service is designed to improve load times and combat attacks, using a network of servers spread throughout the world.
Akamai later tweeted: “We have implemented a fix for this issue and based on current observations, the service is resuming normal operations.
“We continue to monitor the situation and can confirm that this was not the result of a cyber attack on the Akamai platform.”
The incident follows a similar outage six weeks ago, which affected prominent websites, including gov.uk.
US-based Fastly said that the problems experienced on June 8 were due to an “undiscovered software bug” on their system that was caused by a single anonymous customer updating their settings.