There are several causes for this particular problem. The first thing to try is to switch the box off and back on again using the power switch at the back of the box.
Please can you let us know after you have tried this whether this resolves the issue or whether the same issue occurs.
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I've run diagnostics on your account and I can see an issue with your Upstream and Downstream power levels that will need adjusting. I've sent you a private message (purple envelope at the top right of your screen) so I can arrange for a technician to take a look.
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