One of the first things you should do when your broadband stops working is check your router.
Those blinking amber and flashing blue lights aren't just for decoration - each has a specific purpose, from notifying you of a problem with wi-fi, to connection issues, updates, and a failed logins to your account.
We've gathered together information from the biggest broadband providers to show you how to diagnose and fix the problem. And if it can't be resolved straight away, you'll be armed with valuable information to give to your provider, which may help them get you up and running more quickly.
Using an older router? You'll want to make sure it's still getting important security patches to protect against threats. Read our guide on router security for more.
Problems with your BT router
BT Smart Hub and Ultrafast Smart Hub
These hubs only have one light in the centre of the router, as shown above. Different colours mean different things.
No light means the power is off, or you've turned the lights off. Check the router is plugged in, and if everything else seems in place it's time to call BT.
A green light means it's starting up. This should change after a few minutes.
Flashing orange means it's connecting to broadband. This takes around 30 seconds and should change after.
Steady orange means the hub is working but it's not connected to the internet. Try connecting to the hub via ethernet or wi-fi and running BT's on-screen help wizard.
A blue light means the hub is working fine. If the wi-fi doesn't work on your device it could be a problem with your laptop or phone.
Flashing purple means the hub isn't connected to the internet. Check your cables. If it's still not working contact BT.
A red light means there is a problem somewhere. Try restarting, and if it doesn't turn blue, call BT.
BT Home Hub 4 and 5
These older routers have one central light that helps you determine an issue, but they also have broadband and wireless icon lights that appear when there's a problem. Different colours mean different things.
No light means the power is off, so check it's plugged in correctly at the wall and to the router itself. If that doesn't work call BT.
A green light or flashing green means it's starting up. This should change after a few minutes.
Blue light means the hub is working fine. If the wi-fi doesn't work on your device, it could be a problem with your laptop or phone.
An orange light means there is a problem somewhere. Try restarting it and if it doesn't turn blue call BT.
Red light means you're not connected to broadband. Check your cables. If it's still not working, contact BT.
If the broadband light (shaped like a 'b') is orange you're connected but your account may not be active yet.
If the broadband light is red you've failed to login to your account.
If the broadband light is flashing red there's a problem with your broadband line. Check all of your cables.
If the wireless light (this looks like the wireless logo) is orange you've switched off wireless on one or both channels.
If the wireless light is flashing orange your hub is in WPS automatic connection mode.
Sky has three different routers depending on when you started using its services and the type of contract you have.
Sky Q Hub
The most recent addition to Sky's router collection. This square hub has three lights on the right of the device labelled 'power', 'internet' and 'wireless'. Start by checking the power light.
If the power light is off, the router is receiving no power. Check it's plugged in.
If the power button is red, it has a power issue, call Sky for help.
If the power button is flashing amber, your hub is in recovery mode. This can happen after a software upgrade. Reset it using the reset button on the back and it should start working again. If not, download Sky's router recovery tool to restore the software.
If the power light is green but the internet light is off or amber, it's not connected to the internet. Disconnect your router from all of the connections to the phoneline and microfilter. Plug the microfilter back into the master socket then plug the router into the microfilter. This should get it working again.
This boxy, square router has white lights on one end. The power button and internet button (that looks like a smiley face) are the easiest way to tell if your router is working.
If the power button isn't lit, your router is receiving no power. Check it's plugged in.
If the power button is white and the internet button is also white your router is working. If the internet light is off or flashing amber, run a diagnosis.
If the power button is flashing white, your hub is installing a software upgrade. Keep it on.
If the power button is steady amber, it has a power issue, call Sky for help.
If the power button is flashing amber your hub is in recovery mode. This can happen after a software upgrade. Reset it using the reset button on the back and it should start working again. If not, download Sky's router recovery tool to restore the software.
This long flat router has four different lights on the front of the device. The standby button, test button, wi-fi button and internet button.
If all of these lights are off it means your router isn't receiving any power. Check it's plugged in.
If the internet light is green your router is connected to the internet and sending or receiving data. If the wireless light is green too, a wireless device is connected to the router and using the wi-fi.
If the internet light is flashing amber your router is not connected to the internet. Sky has a diagnostic tool which may help you fix this.
If the power and test lights are flashing green, the router is installing a software upgrade. Keep it on.
Virgin Media has four different routers depending on when you became a customer and the type of broadband service you have. The three Super Hubs (Super Hub 2ac, Super Hub 2 and Super Hub) are very similar, so we've grouped them together.
This boxy router has a distinctive front panel. It has three green lights that show in its front panel and a white light at the base that is on all the time. If any lights other than the base light are on there is a problem.
If the wi-fi light (the wi-fi logo) is flashing red or remains green after the two minute startup, there's an issue with the wi-fi.
If the internet light (two arrows) is flashing for a long time it could be acquiring a connection. Once connected it should turn off, but if it doesn't, there's an issue with the internet connection.
If your phone service comes through the hub, the phone light (a phone) will show when there's an issue with the phone service.
The base light should be on all the time - it will be magenta when in modem mode and white on router mode.
(Super Hub 2ac, Super Hub 2 and Super Hub)
These routers have three lights on a side panel: traffic (arrows), ready (a tick) and wireless, which you can use to work out if there's an issue. To check they're working properly you should work down from the traffic light.
If the traffic light is flashing green or blue, data is being transmitted and it should be working.
If the ready light is off, the router isn't connected to the internet. Check the router is plugged in and properly connected.
If the wireless light is solid green or blinking, it is working properly. If the wireless light isn't lit a few minutes after startup, it's not working, so try restarting the router. If this doesn't work contact Virgin Media or check its advice page.
Some models - like the Super Hub 2ac shown above - have two additional lights at the top that tell you which wireless channel the router is user. The very top one indicates that the router is using the 5GHz frequency, while the second one down indicates that the 2.4GHz wireless frequency is in use. If your wi-fi seems slow, try resetting your router and it will automatically choose the channel that is the least congested.
If you're with another broadband provider or have a router you bought yourself, it's always best to check the lights if there is a problem. In general, green lights are good and red or amber lights are bad. Usually, no lights mean your router isn't getting any power.
It's a good idea to keep the instruction manual to hand, or bookmark or print an advice page from the manufacturer or provider's website that explains what your particular router lights mean. That way you can refer to them if you see any problems, and possibly fix the issue yourself. If you do need to get online in the meantime, see our guide on how to set up a mobile phone wi-fi hotspot for a useful temporary solution.