why do bt advise you to use the ethernet connection in preferance to usb I have trouble with my ethernet dropping in and out on my best pc ,so I use my old one for the internet using the usb outlet which seems rock solid I just wondered And if you read this AC ime not touching anything just curious (honest)
because ethernet is designed for connecting to networks (the internet) usb ports are designed for connecting to devices. so they are just recommending you use the Ethernet because that's it's intended purpose.
and when you say the ethernet keeps dropping out that is almost definitely going to be a faulty cable, have you tried another?