@Lampard68
As you have Sky Fibre and if it is the ONT that is showing a red light then have a read of this:
https://helpforum.sky.com/t5/Broadband-Talk/Can-t-connect-to-broadband-and-have-a-red-light-on-your-...
If nothing there helps then the first thing to check is this link to see if there are any outages in your area, it can be a bit slow at picking up issues so if nothing shows perhaps try it again later:
https://www.sky.com/servicechecker
If there isn't try running the line test here:
https://www.sky.com/help/articles/broadband-diagnostic-start
You can also run the test via the MySky app on a mobile data connection.
After this has finished and if it reports back all is good click on broadband to run an updated test. If you get amber or red please follow the on screen instructions.
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