About a year ago, my mum upgraded her internet to full fibre. A new cable was run from the telephone pole to a box on the front of the house, then into the house to another small box with green lights on it. The existing phone plugged, via an adaptor/filter, into the back of the router. She now has two cables running from the telephone pole. Would it cause problems if I removed the original cable that goes to the old master socket?

