O2 not working: Why is 4G and data down on giffgaff and Tesco's networks?

O2's network has stopped working, leaving its customers unable to access the internet.

The issues apply not only to O2 customers but to people on GiffGaff and Tesco Mobile, too.

The cause of the problems is still largely mysterious. O2 said that it is aware of them, is working on a fix, and has suggested they are related to problems at a third-party supplier that have affected other networks around the world.

It is not the first time O2 has been hit by such issues, which appear to be a problem with the infrastructure powering its service.

The company has posted a series of messages making clear that it is working to fix the problems – though without explaining what is wrong.

"Our technical teams are investigating reports of issues when using data," O2's status page said. "Voice calls are working OK. Our technical teams are investigating.

"We apologise for any inconvenience. Updates will be shared here as soon they are available."

A similar explanation was tweeted by O2's official account.

"We are aware our customers are unable to use data this morning," it posted. "Our technical teams are working on the issue with high priority. We are really sorry and working as hard and as fast as we can to fix this."

It then posted a follow-up explaining the problem.

"Outage Update: One of our 3rd party suppliers has identified a software issue in their system," it tweeted. "Our technical teams are working extremely hard to resolve this. We'd encourage you to use Wi-Fi wherever you can and we are really sorry."

If you have been hit by the issues, there may be little you can do. But here are some things to try in the meantime.

While many people switch to GiffGaff or O2 for the deals, it is far from the most reliable of the data networks.

According to Which, EE has the most reliable 4G, with people being able to get faster connections 87 per cent of the time. It also has faster mobile web connections than O2, according to the same survey.

WiFi connections are still working, which might be little consolation if you're already out and trying to connect to the internet.

But it is worth trying to see if you can get online using one: remember, for instance, you can get online at Tube stations by using their WiFi connections, and there might be open networks available if you are near a business. O2 customers may even have access to BT Openzone, which borrows people's in-home WiFi connections to allow you to get onto the internet.

Once you're at work, you might also find there's a WiFi connection for employees that you've never had to use because you can usually get data. Now that you can't get data, it might be helpful to use that instead.

When you're trying to fix your own data, there's not a great deal you can do. Sometimes, switching the connection on and off sometimes fixes problems like these – but isn't working this time around.

Instead, you might just have to stay glued to The Independent's coverage for notification of when the network gets back up again.