Unless you have already opted out, it is entirely likely that your hub is acting as public hotspot that any Virgin Media customer can access when in range. Don't worry, it operates on a separate network to yours and they can't see your devices or data. You can opt out of the Hotspot scheme if you wish ... it's a setting in My Virgin Media.
The settings Admin password, which protects settings changes, & the WiFi password that polices your devices access to the internet.
The Admin password on the base is a factory set "one-time" password that has to be changed the first time you use it anyway.
The WiFi password shoud be ok as long as you don't give it to anyone else.
All VMs latest hubs also double up as a WiFi Hotspot. This is a totally seperate 10Mb connection from your own WiFi, & is only available to other Virgin Customers with Broadband accounts. Incidently, Hotspot users never know where the Hotspot is they are using. It could be your hub, your neighbours, or another in a house across the street. All they see is "Virgin Media" in the network ID.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.