Welcome to Vodafone Community
There seems to be an unknown user logged into my wifi hub. Changed password, went away. But then he is back. Have no idea how and where they are
Through the web admin, in expert mode > WiFi > MAC Filter you can ban a device by it's MAC address!
When you've done that, you may actually find it's something innocuous. For example I have a device on my network that identifies it self as "Sandal", had me scratching my head until I figured out it's a smart hub!