There have been a number of threads started about this in the recent past.
I myself have a Hub One which makes this noise as well, so I know exactly what you are referring to. To put your mind at ease, all of the information we have had from our vendors indicates no performance related issues connected to this noise, and the product is not faulty.
We suggest disabling the 5Ghz frequency in the router settings GUI as this has proved a way of reducing the noise - you can find out how to do this here
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