Hi E-M-G,
Thank you for your post.
Unfortunately it's not something we could say for certain from here - for a device to be connected to your hub it would have need to have inputted the password. If this isn't something you're aware of I would recommend changing the hubs password. You can do that by following this link here: https://www.virginmedia.com/help/broadband/change-wifi-name-and-password
A factory/pin hole reset of the hub is advisable as well as this would remove any devices connected. Once you have done that you would need to re-input passwords into any devices you would like to re-connect.
Cheers,
Ryan.
