I am guessing you never accessed the router menu therefore still at default settings with Wi-Fi on.
You need to enter this on the top browser

Enter the password at this this screen. If 1st time you will need to use the password at the base of the hub3

And below should confirm Wi-Fi on or off.

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M200 Oomph - 5GB SIM + 3 extra SIM family plan - BT whole Wi-Fi - Sky Q
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Don't cry over Virgin price increase instead speak to retentions team and negotiate a better deal.